diff --git a/examples/inception/prepare_config.py b/examples/inception/prepare_config.py
index fb5bcfbfb..03b39de67 100644
--- a/examples/inception/prepare_config.py
+++ b/examples/inception/prepare_config.py
@@ -6,6 +6,8 @@
 import platform
 from pathlib import Path
 
+from olive.common.constants import OS
+
 
 def resolve_windows_config():
 
@@ -18,5 +20,5 @@ def resolve_windows_config():
 
 
 if __name__ == "__main__":
-    if platform.system() == "Windows":
+    if platform.system() == OS.WINDOWS:
         resolve_windows_config()
diff --git a/examples/mobilenet/prepare_config.py b/examples/mobilenet/prepare_config.py
index 3345d4e7d..1ead99d1e 100644
--- a/examples/mobilenet/prepare_config.py
+++ b/examples/mobilenet/prepare_config.py
@@ -7,6 +7,8 @@
 import platform
 from pathlib import Path
 
+from olive.common.constants import OS
+
 
 def raw_qnn_config():
     # pylint: disable=redefined-outer-name
@@ -16,20 +18,20 @@ def raw_qnn_config():
 
     sys_platform = platform.system()
 
-    if sys_platform == "Linux":
+    if sys_platform == OS.LINUX:
         raw_qnn_config["passes"]["qnn_context_binary"] = {
             "type": "QNNContextBinaryGenerator",
             "config": {"backend": "libQnnHtp.so"},
         }
         raw_qnn_config["pass_flows"].append(["converter", "build_model_lib", "qnn_context_binary"])
         raw_qnn_config["passes"]["build_model_lib"]["config"]["lib_targets"] = "x86_64-linux-clang"
-    elif sys_platform == "Windows":
+    elif sys_platform == OS.WINDOWS:
         raw_qnn_config["passes"]["build_model_lib"]["config"]["lib_targets"] = "x86_64-windows-msvc"
 
     for metric_config in raw_qnn_config["evaluators"]["common_evaluator"]["metrics"]:
-        if sys_platform == "Windows":
+        if sys_platform == OS.WINDOWS:
             metric_config["user_config"]["inference_settings"]["qnn"]["backend"] = "QnnCpu"
-        elif sys_platform == "Linux":
+        elif sys_platform == OS.LINUX:
             metric_config["user_config"]["inference_settings"]["qnn"]["backend"] = "libQnnCpu"
 
     with Path("raw_qnn_sdk_config.json").open("w") as f:
diff --git a/examples/phi2/phi2.py b/examples/phi2/phi2.py
index 72c92a169..3693a17c8 100644
--- a/examples/phi2/phi2.py
+++ b/examples/phi2/phi2.py
@@ -11,6 +11,7 @@
 from onnxruntime import __version__ as OrtVersion
 from packaging import version
 
+from olive.common.constants import OS
 from olive.workflows import run as olive_run
 
 # flake8: noqa: T201
@@ -30,25 +31,25 @@
         # -1 to use CPU
         "device_id": -1,
         "use_fp16": False,
-        "use_step": platform.system() == "Linux",
+        "use_step": platform.system() == OS.LINUX,
     },
     "cpu_int4": {
         "use_buffer_share": False,
         "device_id": -1,
         "use_fp16": False,
-        "use_step": platform.system() == "Linux",
+        "use_step": platform.system() == OS.LINUX,
     },
     "cuda_fp16": {
         "use_buffer_share": False,
         "device_id": 0,
         "use_fp16": True,
-        "use_step": platform.system() == "Linux",
+        "use_step": platform.system() == OS.LINUX,
     },
     "cuda_int4": {
         "use_buffer_share": False,
         "device_id": 0,
         "use_fp16": True,
-        "use_step": platform.system() == "Linux",
+        "use_step": platform.system() == OS.LINUX,
     },
 }
 
@@ -180,7 +181,7 @@ def main(raw_args=None):
         with open(json_file_template) as f:
             template_json = json.load(f)
 
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             legacy_optimization_setting(template_json)
 
         # add pass flows
diff --git a/examples/test/test_bert_ptq_cpu_docker.py b/examples/test/test_bert_ptq_cpu_docker.py
index 608fb91d9..d5401be20 100644
--- a/examples/test/test_bert_ptq_cpu_docker.py
+++ b/examples/test/test_bert_ptq_cpu_docker.py
@@ -9,6 +9,8 @@
 import pytest
 from utils import check_output, patch_config
 
+from olive.common.constants import OS
+
 
 @pytest.fixture(scope="module", autouse=True)
 def setup():
@@ -25,7 +27,7 @@ def setup():
 @pytest.mark.parametrize("system", ["docker_system"])
 @pytest.mark.parametrize("olive_json", ["bert_ptq_cpu.json"])
 def test_bert(search_algorithm, execution_order, system, olive_json):
-    if system == "docker_system" and platform.system() == "Windows":
+    if system == "docker_system" and platform.system() == OS.WINDOWS:
         pytest.skip("Skip Linux containers on Windows host test case.")
 
     from olive.workflows import run as olive_run
diff --git a/examples/test/test_qnn_tooklit.py b/examples/test/test_qnn_tooklit.py
index c7739f1c7..41c62681f 100644
--- a/examples/test/test_qnn_tooklit.py
+++ b/examples/test/test_qnn_tooklit.py
@@ -9,6 +9,7 @@
 import pytest
 from utils import check_output, download_azure_blob
 
+from olive.common.constants import OS
 from olive.common.utils import retry_func, run_subprocess
 from olive.logging import set_verbosity_debug
 
@@ -20,9 +21,9 @@ class TestQnnToolkit:
     def setup(self, tmp_path):
         """Download the qnn sdk."""
         blob, download_path = "", ""
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             blob, download_path = "qnn_sdk_windows.zip", "qnn_sdk_windows.zip"
-        elif platform.system() == "Linux":
+        elif platform.system() == OS.LINUX:
             blob, download_path = "qnn_sdk_linux.zip", "qnn_sdk_linux.zip"
 
         download_azure_blob(
@@ -32,10 +33,10 @@ def setup(self, tmp_path):
         )
         target_path = tmp_path / "qnn_sdk"
         target_path.mkdir(parents=True, exist_ok=True)
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             cmd = f"powershell Expand-Archive -Path {download_path} -DestinationPath {str(target_path)}"
             run_subprocess(cmd=cmd, check=True)
-        elif platform.system() == "Linux":
+        elif platform.system() == OS.LINUX:
             run_subprocess(cmd=f"unzip {download_path} -d {str(target_path)}", check=True)
 
         os.environ["QNN_SDK_ROOT"] = str(target_path / "opt" / "qcom" / "aistack")
@@ -55,9 +56,9 @@ def _setup_resource(self, use_olive_env):
             )
             # install dependencies
             python_cmd = ""
-            if platform.system() == "Windows":
+            if platform.system() == OS.WINDOWS:
                 python_cmd = str(Path(os.environ["QNN_SDK_ROOT"]) / "olive-pyenv" / "python.exe")
-            elif platform.system() == "Linux":
+            elif platform.system() == OS.LINUX:
                 python_cmd = str(Path(os.environ["QNN_SDK_ROOT"]) / "olive-pyenv" / "bin" / "python")
             install_cmd = [
                 python_cmd,
@@ -69,7 +70,7 @@ def _setup_resource(self, use_olive_env):
             packages = ["tensorflow==2.10.1", "numpy==1.23.5"]
             retry_func(run_subprocess, kwargs={"cmd": f"python -m pip install {' '.join(packages)}", "check": True})
             os.environ["PYTHONPATH"] = str(Path(os.environ["QNN_SDK_ROOT"]) / "lib" / "python")
-            if platform.system() == "Linux":
+            if platform.system() == OS.LINUX:
                 os.environ["PATH"] = (
                     str(Path(os.environ["QNN_SDK_ROOT"]) / "bin" / "x86_64-linux-clang")
                     + os.path.pathsep
diff --git a/examples/test/test_snpe_toolkit.py b/examples/test/test_snpe_toolkit.py
index 597e0531c..27afb8028 100644
--- a/examples/test/test_snpe_toolkit.py
+++ b/examples/test/test_snpe_toolkit.py
@@ -9,6 +9,7 @@
 import pytest
 from utils import check_output, download_azure_blob
 
+from olive.common.constants import OS
 from olive.common.utils import retry_func, run_subprocess
 from olive.logging import set_verbosity_debug
 
@@ -20,9 +21,9 @@ class TestSnpeToolkit:
     def setup(self, tmp_path):
         """Download the snpe sdk."""
         blob, download_path = "", ""
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             blob, download_path = "snpe_sdk_windows.zip", "snpe_sdk_windows.zip"
-        elif platform.system() == "Linux":
+        elif platform.system() == OS.LINUX:
             blob, download_path = "snpe_sdk_linux.zip", "snpe_sdk_linux.zip"
 
         download_azure_blob(
@@ -32,10 +33,10 @@ def setup(self, tmp_path):
         )
         target_path = tmp_path / "snpe_sdk"
         target_path.mkdir(parents=True, exist_ok=True)
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             cmd = f"powershell Expand-Archive -Path {download_path} -DestinationPath {str(target_path)}"
             run_subprocess(cmd=cmd, check=True)
-        elif platform.system() == "Linux":
+        elif platform.system() == OS.LINUX:
             run_subprocess(cmd=f"unzip {download_path} -d {str(target_path)}", check=True)
         os.environ["SNPE_ROOT"] = str(target_path)
 
@@ -54,9 +55,9 @@ def _setup_resource(self, use_olive_env):
             )
             # install dependencies
             python_cmd = ""
-            if platform.system() == "Windows":
+            if platform.system() == OS.WINDOWS:
                 python_cmd = str(Path(os.environ["SNPE_ROOT"]) / "olive-pyenv" / "python.exe")
-            elif platform.system() == "Linux":
+            elif platform.system() == OS.LINUX:
                 python_cmd = str(Path(os.environ["SNPE_ROOT"]) / "olive-pyenv" / "bin" / "python")
             install_cmd = [
                 python_cmd,
@@ -68,7 +69,7 @@ def _setup_resource(self, use_olive_env):
             packages = ["tensorflow==2.10.1", "numpy==1.23.5"]
             retry_func(run_subprocess, kwargs={"cmd": f"python -m pip install {' '.join(packages)}", "check": True})
             os.environ["PYTHONPATH"] = str(Path(os.environ["SNPE_ROOT"]) / "lib" / "python")
-            if platform.system() == "Linux":
+            if platform.system() == OS.LINUX:
                 os.environ["PATH"] = (
                     str(Path(os.environ["SNPE_ROOT"]) / "bin" / "x86_64-linux-clang")
                     + os.path.pathsep
diff --git a/examples/test/test_whisper.py b/examples/test/test_whisper.py
index d27e5b74f..b3ff6a898 100644
--- a/examples/test/test_whisper.py
+++ b/examples/test/test_whisper.py
@@ -11,6 +11,8 @@
 import pytest
 from utils import check_output
 
+from olive.common.constants import OS
+
 
 @pytest.fixture(scope="module", autouse=True)
 def setup():
@@ -34,7 +36,7 @@ def setup():
 def test_whisper(device_precision):
     from olive.workflows import run as olive_run
 
-    if platform.system() == "Windows" and device_precision[1].startswith("inc_int8"):
+    if platform.system() == OS.WINDOWS and device_precision[1].startswith("inc_int8"):
         pytest.skip("Skip test on Windows. neural-compressor import is hanging on Windows.")
 
     device, precision = device_precision
diff --git a/examples/vgg/prepare_config.py b/examples/vgg/prepare_config.py
index b6039053b..78aa223a6 100644
--- a/examples/vgg/prepare_config.py
+++ b/examples/vgg/prepare_config.py
@@ -6,6 +6,8 @@
 import platform
 from pathlib import Path
 
+from olive.common.constants import OS
+
 
 def resolve_windows_config():
 
@@ -18,5 +20,5 @@ def resolve_windows_config():
 
 
 if __name__ == "__main__":
-    if platform.system() == "Windows":
+    if platform.system() == OS.WINDOWS:
         resolve_windows_config()
diff --git a/olive/common/constants.py b/olive/common/constants.py
index 30c382ffd..ede2ec842 100644
--- a/olive/common/constants.py
+++ b/olive/common/constants.py
@@ -2,5 +2,11 @@
 # Copyright (c) Microsoft Corporation. All rights reserved.
 # Licensed under the MIT License.
 # --------------------------------------------------------------------------
+from enum import Enum
 
 DEFAULT_WORKFLOW_ID = "default_workflow"
+
+
+class OS(str, Enum):
+    WINDOWS = "Windows"
+    LINUX = "Linux"
diff --git a/olive/common/utils.py b/olive/common/utils.py
index 438c4df83..12fd4d95a 100644
--- a/olive/common/utils.py
+++ b/olive/common/utils.py
@@ -18,6 +18,8 @@
 from pathlib import Path
 from typing import Dict, List, Tuple, Union
 
+from olive.common.constants import OS
+
 logger = logging.getLogger(__name__)
 
 
@@ -25,7 +27,7 @@ def run_subprocess(cmd, env=None, cwd=None, check=False):
     logger.debug("Running command: %s", cmd)
 
     assert isinstance(cmd, (str, list)), f"cmd must be a string or a list, got {type(cmd)}."
-    windows = platform.system() == "Windows"
+    windows = platform.system() == OS.WINDOWS
     if isinstance(cmd, str):
         # In posix model, the cmd string will be handled with specific posix rules.
         # https://docs.python.org/3.8/library/shlex.html#parsing-rules
diff --git a/olive/engine/packaging/packaging_generator.py b/olive/engine/packaging/packaging_generator.py
index cc8121c51..10db30a96 100644
--- a/olive/engine/packaging/packaging_generator.py
+++ b/olive/engine/packaging/packaging_generator.py
@@ -16,6 +16,7 @@
 
 import pkg_resources
 
+from olive.common.constants import OS
 from olive.common.utils import copy_dir, retry_func, run_subprocess
 from olive.engine.packaging.packaging_config import (
     AzureMLDeploymentPackagingConfig,
@@ -707,14 +708,14 @@ def _download_ort_extensions_package(use_ort_extensions: bool, download_path: st
         # Hardcode the nightly version number for now until we have a better way to identify nightly version
         if version.startswith("0.8.0."):
             system = platform.system()
-            if system == "Windows":
+            if system == OS.WINDOWS:
                 download_command = (
                     f"{sys.executable} -m pip download -i "
                     "https://aiinfra.pkgs.visualstudio.com/PublicPackages/_packaging/ORT-Nightly/pypi/simple/ "
                     f"onnxruntime-extensions=={version} --no-deps -d {download_path}"
                 )
                 run_subprocess(download_command)
-            elif system == "Linux":
+            elif system == OS.LINUX:
                 logger.warning(
                     "ONNXRuntime-Extensions nightly package is not available for Linux. "
                     "Skip packaging ONNXRuntime-Extensions package. Please manually install ONNXRuntime-Extensions."
diff --git a/olive/model/handler/qnn.py b/olive/model/handler/qnn.py
index 873990be6..7b1645f41 100644
--- a/olive/model/handler/qnn.py
+++ b/olive/model/handler/qnn.py
@@ -7,6 +7,7 @@
 from pathlib import Path
 from typing import Any, Callable, Dict, List, Optional, Tuple, Union
 
+from olive.common.constants import OS
 from olive.constants import Framework, ModelFileFormat
 from olive.hardware.accelerator import Device
 from olive.model.config import IoConfig
@@ -55,10 +56,10 @@ def model_path(self):
                 logger.debug(
                     "QNNModelHandler: lib_targets is not provided, using default lib_targets x86_64-linux-clang"
                 )
-                if platform.system() == "Linux":
+                if platform.system() == OS.LINUX:
                     lib_targets = "x86_64-linux-clang"
                     model_lib_suffix = ".so"
-                elif platform.system() == "Windows":
+                elif platform.system() == OS.WINDOWS:
                     # might be different for arm devices
                     lib_targets = "x64"
                     model_lib_suffix = ".dll"
diff --git a/olive/passes/qnn/context_binary_generator.py b/olive/passes/qnn/context_binary_generator.py
index 417a4cf7a..30649fa7d 100644
--- a/olive/passes/qnn/context_binary_generator.py
+++ b/olive/passes/qnn/context_binary_generator.py
@@ -8,6 +8,7 @@
 from pathlib import Path
 from typing import Any, Dict
 
+from olive.common.constants import OS
 from olive.constants import ModelFileFormat
 from olive.hardware import AcceleratorSpec
 from olive.model import QNNModelHandler
@@ -26,7 +27,7 @@ class QNNContextBinaryGenerator(Pass):
 
     @classmethod
     def _default_config(cls, accelerator_spec: AcceleratorSpec) -> Dict[str, PassConfigParam]:
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             raise NotImplementedError("QNNContextBinaryGenerator is not supported on Windows.")
 
         return {
diff --git a/olive/passes/qnn/conversion.py b/olive/passes/qnn/conversion.py
index 1aca52523..ce7885f49 100644
--- a/olive/passes/qnn/conversion.py
+++ b/olive/passes/qnn/conversion.py
@@ -7,6 +7,7 @@
 from pathlib import Path
 from typing import Any, Dict, List, Union
 
+from olive.common.constants import OS
 from olive.constants import ModelFileFormat
 from olive.hardware import AcceleratorSpec
 from olive.model import ONNXModelHandler, PyTorchModelHandler, QNNModelHandler, TensorFlowModelHandler
@@ -82,7 +83,7 @@ def _run_for_config(
         converter_program = [f"qnn-{converter_platform}-converter"]
 
         runner = QNNSDKRunner(use_dev_tools=True)
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             converter_program = [
                 "python",
                 str(Path(runner.sdk_env.sdk_root_path) / "bin" / runner.sdk_env.target_arch / converter_program[0]),
diff --git a/olive/passes/qnn/model_lib_generator.py b/olive/passes/qnn/model_lib_generator.py
index dcbe1a343..d835b579c 100644
--- a/olive/passes/qnn/model_lib_generator.py
+++ b/olive/passes/qnn/model_lib_generator.py
@@ -8,6 +8,7 @@
 from pathlib import Path
 from typing import Any, Dict
 
+from olive.common.constants import OS
 from olive.constants import ModelFileFormat
 from olive.hardware import AcceleratorSpec
 from olive.model import QNNModelHandler
@@ -53,7 +54,7 @@ def _run_for_config(
     ) -> QNNModelHandler:
         main_cmd = "qnn-model-lib-generator"
         runner = QNNSDKRunner(use_dev_tools=True)
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             main_cmd = "python " + str(
                 Path(runner.sdk_env.sdk_root_path) / "bin" / runner.sdk_env.target_arch / main_cmd
             )
diff --git a/olive/platform_sdk/qualcomm/configure/configure.py b/olive/platform_sdk/qualcomm/configure/configure.py
index 5a977cb8b..9ac79dd10 100644
--- a/olive/platform_sdk/qualcomm/configure/configure.py
+++ b/olive/platform_sdk/qualcomm/configure/configure.py
@@ -10,6 +10,7 @@
 from importlib import resources
 from pathlib import Path
 
+from olive.common.constants import OS
 from olive.common.utils import run_subprocess
 from olive.platform_sdk.qualcomm.constants import SDKTargetDevice
 from olive.platform_sdk.qualcomm.qnn.env import QNNSDKEnv
@@ -31,14 +32,14 @@ def configure_dev(py_version: str, sdk: str):
     if sdk_arch not in (SDKTargetDevice.x86_64_linux, SDKTargetDevice.x86_64_windows):
         return
 
-    script_name = "create_python_env.sh" if platform.system() == "Linux" else "create_python_env.ps1"
+    script_name = "create_python_env.sh" if platform.system() == OS.LINUX else "create_python_env.ps1"
 
     logger.info("Configuring %s for %s with python %s...", sdk, sdk_arch, py_version)
     cmd = None
     with resources.path(resource_path, script_name) as create_python_env_path:
-        if platform.system() == "Linux":
+        if platform.system() == OS.LINUX:
             cmd = f"bash {create_python_env_path} -v {py_version} --sdk {sdk}"
-        elif platform.system() == "Windows":
+        elif platform.system() == OS.WINDOWS:
             cmd = f"powershell {create_python_env_path} {py_version} {sdk}"
         run_subprocess(cmd, check=True)
     logger.info("Done")
diff --git a/olive/platform_sdk/qualcomm/env.py b/olive/platform_sdk/qualcomm/env.py
index 3746535d8..b89a96ae9 100644
--- a/olive/platform_sdk/qualcomm/env.py
+++ b/olive/platform_sdk/qualcomm/env.py
@@ -7,6 +7,7 @@
 import platform
 from pathlib import Path
 
+from olive.common.constants import OS
 from olive.platform_sdk.qualcomm.constants import SDKTargetDevice
 
 
@@ -37,14 +38,14 @@ def _infer_target_arch(self, fail_on_unsupported: bool = True) -> str:
         """Infer the target architecture from the SDK root path based on platform and processor."""
         system = platform.system()
         target_arch = None
-        if system == "Linux":
+        if system == OS.LINUX:
             machine = platform.machine()
             if machine == "x86_64":
                 target_arch = SDKTargetDevice.x86_64_linux
             else:
                 if fail_on_unsupported:
                     raise ValueError(f"Unsupported machine {machine} on system {system}")
-        elif system == "Windows":
+        elif system == OS.WINDOWS:
             processor_identifier = os.environ.get("PROCESSOR_IDENTIFIER", "")
             if "ARM" in processor_identifier:
                 target_arch = SDKTargetDevice.arm64x_windows
@@ -84,7 +85,7 @@ def env(self):
         if platform.system() == "Linux":
             bin_path += delimiter + "/usr/bin"
             env["LD_LIBRARY_PATH"] = lib_path
-        elif platform.system() == "Windows":
+        elif platform.system() == OS.WINDOWS:
             bin_path += delimiter + lib_path
 
         env["PATH"] = bin_path
diff --git a/olive/platform_sdk/qualcomm/qnn/env.py b/olive/platform_sdk/qualcomm/qnn/env.py
index 5854a5b1b..045edb658 100644
--- a/olive/platform_sdk/qualcomm/qnn/env.py
+++ b/olive/platform_sdk/qualcomm/qnn/env.py
@@ -7,6 +7,7 @@
 import platform
 from pathlib import Path
 
+from olive.common.constants import OS
 from olive.platform_sdk.qualcomm.env import SDKEnv
 
 
@@ -19,7 +20,7 @@ def env(self):
         env = super().env
         sdk_root_path = self.sdk_root_path
         delimiter = os.path.pathsep
-        python_env_parent_folder = "Scripts" if platform.system() == "Windows" else "bin"
+        python_env_parent_folder = "Scripts" if platform.system() == OS.WINDOWS else "bin"
         python_env_bin_path = str(Path(f"{sdk_root_path}/olive-pyenv/{python_env_parent_folder}"))
 
         env["PATH"] += delimiter + os.environ["PATH"]
@@ -31,7 +32,7 @@ def env(self):
                     " to add the missing file."
                 )
             env["PATH"] = python_env_bin_path + delimiter + env["PATH"]
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             for k, v in os.environ.items():
                 if k not in env:
                     env[k] = v
@@ -41,7 +42,7 @@ def env(self):
     def get_qnn_backend(self, backend_name):
         backend_path = Path(self.sdk_root_path) / "lib" / self.target_arch / backend_name
         backend_path = (
-            backend_path.with_suffix(".dll") if platform.system() == "Windows" else backend_path.with_suffix(".so")
+            backend_path.with_suffix(".dll") if platform.system() == OS.WINDOWS else backend_path.with_suffix(".so")
         )
 
         if not backend_path.exists():
diff --git a/olive/platform_sdk/qualcomm/qnn/qnn.py b/olive/platform_sdk/qualcomm/qnn/qnn.py
index 6cd7af359..78bd0c25c 100644
--- a/olive/platform_sdk/qualcomm/qnn/qnn.py
+++ b/olive/platform_sdk/qualcomm/qnn/qnn.py
@@ -13,6 +13,7 @@
 import numpy as np
 
 from olive.common.config_utils import ConfigBase
+from olive.common.constants import OS
 from olive.constants import ModelFileFormat
 from olive.platform_sdk.qualcomm.runner import QNNSDKRunner
 from olive.platform_sdk.qualcomm.utils.input_list import get_input_ids
@@ -128,7 +129,7 @@ def _parse_model_output(self, output_dir, input_list, tmp_dir_path):
             # copy the raw file to the workspace and rename it
             if output_dir is not None:
                 output_file = output_dir / f"{input_id}.raw"
-                if platform.system() == "Windows":
+                if platform.system() == OS.WINDOWS:
                     output_file = output_dir / f"{input_id}.raw".replace(":", "_")
                 raw_file.rename(output_file)
                 result_files.append((input_id, output_file))
diff --git a/olive/platform_sdk/qualcomm/runner.py b/olive/platform_sdk/qualcomm/runner.py
index bb3781adb..27614f01d 100644
--- a/olive/platform_sdk/qualcomm/runner.py
+++ b/olive/platform_sdk/qualcomm/runner.py
@@ -10,6 +10,7 @@
 from pathlib import Path
 from typing import List, Union
 
+from olive.common.constants import OS
 from olive.common.utils import run_subprocess
 from olive.platform_sdk.qualcomm.qnn.env import QNNSDKEnv
 from olive.platform_sdk.qualcomm.snpe.env import SNPESDKEnv
@@ -49,11 +50,11 @@ def _resolve_cmd(self, cmd: Union[str, List[str]]) -> List[str]:
         import platform
 
         if isinstance(cmd, str):
-            cmd_list = shlex.split(cmd, posix=(platform.system() != "Windows"))
+            cmd_list = shlex.split(cmd, posix=(platform.system() != OS.WINDOWS))
         else:
             cmd_list = cmd
 
-        if platform.system() == "Windows" and cmd_list[0].startswith(("snpe-", "qnn-")):
+        if platform.system() == OS.WINDOWS and cmd_list[0].startswith(("snpe-", "qnn-")):
             logger.debug("Resolving command %s on Windows.", cmd_list)
             cmd_dir = Path(self.sdk_env.sdk_root_path) / "bin" / self.sdk_env.target_arch
             cmd_name = cmd_list[0]
diff --git a/olive/platform_sdk/qualcomm/snpe/env.py b/olive/platform_sdk/qualcomm/snpe/env.py
index 5fd5c9c87..89d11e4c8 100644
--- a/olive/platform_sdk/qualcomm/snpe/env.py
+++ b/olive/platform_sdk/qualcomm/snpe/env.py
@@ -7,6 +7,7 @@
 import platform
 from pathlib import Path
 
+from olive.common.constants import OS
 from olive.platform_sdk.qualcomm.constants import SDKTargetDevice
 from olive.platform_sdk.qualcomm.env import SDKEnv
 
@@ -21,7 +22,7 @@ def env(self):
         target_arch = self.target_arch
         sdk_root_path = self.sdk_root_path
         delimiter = os.path.pathsep
-        python_env_parent_folder = "" if platform.system() == "Windows" else "bin"
+        python_env_parent_folder = "" if platform.system() == OS.WINDOWS else "bin"
         python_env_bin_path = str(Path(f"{sdk_root_path}/olive-pyenv/{python_env_parent_folder}"))
 
         env["PATH"] += delimiter + os.environ["PATH"]
@@ -35,7 +36,7 @@ def env(self):
 
             env["PATH"] = python_env_bin_path + delimiter + env["PATH"]
 
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             os_env = os.environ.copy()
             os_env.update(env)
             env = os_env
diff --git a/olive/platform_sdk/qualcomm/snpe/tools/dev.py b/olive/platform_sdk/qualcomm/snpe/tools/dev.py
index b761b7e53..9ebd07d84 100644
--- a/olive/platform_sdk/qualcomm/snpe/tools/dev.py
+++ b/olive/platform_sdk/qualcomm/snpe/tools/dev.py
@@ -12,6 +12,7 @@
 import onnx
 from onnx import TensorProto, helper
 
+from olive.common.constants import OS
 from olive.platform_sdk.qualcomm.runner import SNPESDKRunner as SNPERunner
 
 logger = logging.getLogger(__name__)
@@ -191,7 +192,7 @@ def quantize_dlc(dlc_path: str, input_list: str, config: dict, output_file: str)
         extra_args: str = extra arguments to pass to the quantizer.
     """
     quant_cmd = "snpe-dlc-quantize"
-    if platform.system() == "Windows":
+    if platform.system() == OS.WINDOWS:
         # snpe-dlc-quant is the Windows version of the quantizer tool
         # and it does not support the --enable_htp flag
         quant_cmd = "snpe-dlc-quant"
@@ -199,7 +200,7 @@ def quantize_dlc(dlc_path: str, input_list: str, config: dict, output_file: str)
     if config["use_enhanced_quantizer"]:
         cmd += " --use_enhanced_quantizer"
     if config["enable_htp"]:
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             logger.warning("--enable_htp is not supported on Windows")
         else:
             cmd += " --enable_htp"
diff --git a/olive/platform_sdk/qualcomm/snpe/tools/inference.py b/olive/platform_sdk/qualcomm/snpe/tools/inference.py
index 4926b2ea8..cdcd17f48 100644
--- a/olive/platform_sdk/qualcomm/snpe/tools/inference.py
+++ b/olive/platform_sdk/qualcomm/snpe/tools/inference.py
@@ -14,6 +14,7 @@
 
 import olive.platform_sdk.qualcomm.snpe.utils.adb as adb_utils
 from olive.common.config_utils import validate_enum
+from olive.common.constants import OS
 from olive.platform_sdk.qualcomm.constants import PerfProfile, ProfilingLevel, SNPEDevice
 from olive.platform_sdk.qualcomm.runner import SNPESDKRunner as SNPERunner
 from olive.platform_sdk.qualcomm.utils.input_list import get_input_ids, resolve_input_list
@@ -97,7 +98,7 @@ def _snpe_net_run_adb(
         adb_utils.run_snpe_adb_command(cmd, android_target, push_snpe, runs=runs, sleep=sleep)
 
         # replace ":" in output filenames with "_" if on windows before pulling
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             rename_cmd = (
                 f"cd {target_output_dir} &&"
                 " find -name '*:*' -exec sh -c 'for x; do mv $x $(echo $x | sed \"s/:/_/g\"); done' _ {} +"
@@ -214,9 +215,9 @@ def snpe_net_run(
 
     # get the delimiter for the output files
     delimiter = None
-    if platform.system() == "Linux":
+    if platform.system() == OS.LINUX:
         delimiter = ":"
-    elif platform.system() == "Windows":
+    elif platform.system() == OS.WINDOWS:
         delimiter = "_"
 
     # dictionary to store the results as numpy arrays
@@ -242,7 +243,7 @@ def snpe_net_run(
             if not (member / output_file_name).exists():
                 # `:0` is already in the output name or source model was not tensorflow
                 output_file_name = f"{output_name}.raw"
-            if platform.system() == "Windows":
+            if platform.system() == OS.WINDOWS:
                 # replace ":" with "_" in the file name.
                 output_file_name = output_file_name.replace(":", "_")
             raw_file = member / output_file_name
@@ -250,7 +251,7 @@ def snpe_net_run(
             # copy the raw file to the workspace and rename it
             if output_dir is not None:
                 output_file = output_dir / f"{input_id}.{output_name}.raw"
-                if platform.system() == "Windows":
+                if platform.system() == OS.WINDOWS:
                     # replace ":" with "_" in the file name.
                     output_file = output_dir / f"{input_id}.{output_name}.raw".replace(":", "_")
                 if len(output_names) == 1:
diff --git a/olive/platform_sdk/qualcomm/snpe/utils/adb.py b/olive/platform_sdk/qualcomm/snpe/utils/adb.py
index 1d69c9a99..9bb7319a0 100644
--- a/olive/platform_sdk/qualcomm/snpe/utils/adb.py
+++ b/olive/platform_sdk/qualcomm/snpe/utils/adb.py
@@ -9,6 +9,7 @@
 from pathlib import Path
 from typing import Tuple
 
+from olive.common.constants import OS
 from olive.common.utils import run_subprocess
 
 logger = logging.getLogger(__name__)
@@ -64,9 +65,9 @@ def run_adb_command(
 
     # platform specific shell command
     if shell_cmd:
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             cmd = f"shell {cmd}"
-        elif platform.system() == "Linux":
+        elif platform.system() == OS.LINUX:
             cmd = f'shell "{cmd}"'
 
     # run the command
diff --git a/olive/systems/python_environment/python_environment_system.py b/olive/systems/python_environment/python_environment_system.py
index a1f4c039d..3d51589bc 100644
--- a/olive/systems/python_environment/python_environment_system.py
+++ b/olive/systems/python_environment/python_environment_system.py
@@ -11,6 +11,7 @@
 from pathlib import Path
 from typing import TYPE_CHECKING, Any, Dict, List, Optional, Union
 
+from olive.common.constants import OS
 from olive.common.utils import run_subprocess
 from olive.evaluator.metric_result import MetricResult
 from olive.model import ModelConfig
@@ -52,7 +53,7 @@ def __init__(
             prepend_to_path=prepend_to_path,
         )
         if olive_managed_env:
-            if platform.system() == "Linux":
+            if platform.system() == OS.LINUX:
                 temp_dir = os.path.join(os.environ.get("HOME", ""), "tmp")
                 if not os.path.exists(temp_dir):
                     os.makedirs(temp_dir)
@@ -189,7 +190,7 @@ def remove(self):
         except FileNotFoundError:
             pass
 
-        if platform.system() == "Linux":
+        if platform.system() == OS.LINUX:
             try:
                 shutil.rmtree(self.environ["TMPDIR"])
                 logger.info("Temporary directory '%s' removed.", self.environ["TMPDIR"])
diff --git a/olive/systems/utils/misc.py b/olive/systems/utils/misc.py
index 514e038a2..b5afaaaa1 100644
--- a/olive/systems/utils/misc.py
+++ b/olive/systems/utils/misc.py
@@ -12,6 +12,7 @@
 from pathlib import Path
 from typing import TYPE_CHECKING, Dict, List, Optional, Union
 
+from olive.common.constants import OS
 from olive.common.utils import hash_dir, run_subprocess
 from olive.hardware import DEFAULT_CPU_ACCELERATOR, AcceleratorSpec
 from olive.hardware.constants import PROVIDER_DOCKERFILE_MAPPING, PROVIDER_PACKAGE_MAPPING
@@ -56,7 +57,7 @@ def create_managed_system(system_config: "SystemConfig", accelerator: "Accelerat
 
         from olive.systems.python_environment import PythonEnvironmentSystem
 
-        if platform.system() == "Linux":
+        if platform.system() == OS.LINUX:
             destination_dir = os.path.join(os.environ.get("HOME", ""), "tmp")
             if not os.path.exists(destination_dir):
                 os.makedirs(destination_dir)
@@ -67,7 +68,7 @@ def create_managed_system(system_config: "SystemConfig", accelerator: "Accelerat
         venv.create(venv_path, with_pip=True, system_site_packages=True)
         logger.info("Virtual environment '%s' created.", venv_path)
 
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             python_environment_path = f"{venv_path}/Scripts"
         else:
             python_environment_path = f"{venv_path}/bin"
diff --git a/test/integ_test/evaluator/docker_eval/test_docker_evaluation.py b/test/integ_test/evaluator/docker_eval/test_docker_evaluation.py
index fe9cc1d1d..25875f042 100644
--- a/test/integ_test/evaluator/docker_eval/test_docker_evaluation.py
+++ b/test/integ_test/evaluator/docker_eval/test_docker_evaluation.py
@@ -21,6 +21,7 @@
 
 import pytest
 
+from olive.common.constants import OS
 from olive.evaluator.metric_result import joint_metric_key
 from olive.hardware import DEFAULT_CPU_ACCELERATOR
 from olive.model import ModelConfig
@@ -55,7 +56,7 @@ def setup(self):
         ("model_type", "model_config_func", "metric_func", "expected_res"),
         EVALUATION_TEST_CASE,
     )
-    @pytest.mark.skipif(platform.system() == "Windows", reason="Docker target does not support windows")
+    @pytest.mark.skipif(platform.system() == OS.WINDOWS, reason="Docker target does not support windows")
     def test_evaluate_model(self, model_type, model_config_func, metric_func, expected_res):
         docker_target = get_docker_target()
         model_config = model_config_func()
diff --git a/test/integ_test/pass_runner/test_docker_system.py b/test/integ_test/pass_runner/test_docker_system.py
index 81e0b3c8a..f6db4ca4d 100644
--- a/test/integ_test/pass_runner/test_docker_system.py
+++ b/test/integ_test/pass_runner/test_docker_system.py
@@ -9,6 +9,7 @@
 
 import pytest
 
+from olive.common.constants import OS
 from olive.hardware.accelerator import DEFAULT_CPU_ACCELERATOR
 from olive.logging import set_default_logger_severity
 from olive.model.config.model_config import ModelConfig
@@ -16,7 +17,7 @@
 from olive.passes.onnx.perf_tuning import OrtPerfTuning
 
 
-@pytest.mark.skipif(platform.system() == "Windows", reason="Docker target does not support windows")
+@pytest.mark.skipif(platform.system() == OS.WINDOWS, reason="Docker target does not support windows")
 @pytest.fixture(scope="module", autouse=True)
 def setup():
     get_directories()
@@ -25,7 +26,7 @@ def setup():
     delete_directories()
 
 
-@pytest.mark.skipif(platform.system() == "Windows", reason="Docker target does not support windows")
+@pytest.mark.skipif(platform.system() == OS.WINDOWS, reason="Docker target does not support windows")
 def test_pass_runner(tmp_path):
     docker_target = get_docker_target()
     model_config = get_onnx_model()
diff --git a/test/multiple_ep/test_aml_system.py b/test/multiple_ep/test_aml_system.py
index 67b34b098..3d4511298 100644
--- a/test/multiple_ep/test_aml_system.py
+++ b/test/multiple_ep/test_aml_system.py
@@ -7,12 +7,13 @@
 
 import pytest
 
+from olive.common.constants import OS
 from olive.model import ModelConfig
 
 # pylint: disable=attribute-defined-outside-init
 
 
-@pytest.mark.skipif(platform.system() == "Windows", reason="Skip test on Windows.")
+@pytest.mark.skipif(platform.system() == OS.WINDOWS, reason="Skip test on Windows.")
 class TestOliveAzureMLSystem:
     @pytest.fixture(autouse=True)
     def setup(self):
diff --git a/test/multiple_ep/test_docker_system.py b/test/multiple_ep/test_docker_system.py
index bd8521908..966c5aa72 100644
--- a/test/multiple_ep/test_docker_system.py
+++ b/test/multiple_ep/test_docker_system.py
@@ -8,13 +8,14 @@
 
 import pytest
 
+from olive.common.constants import OS
 from olive.logging import set_default_logger_severity
 from olive.model import ModelConfig
 
 # pylint: disable=attribute-defined-outside-init
 
 
-@pytest.mark.skipif(platform.system() == "Windows", reason="Docker target does not support windows")
+@pytest.mark.skipif(platform.system() == OS.WINDOWS, reason="Docker target does not support windows")
 class TestOliveManagedDockerSystem:
     @pytest.fixture(autouse=True)
     def setup(self):
diff --git a/test/multiple_ep/test_python_env_system.py b/test/multiple_ep/test_python_env_system.py
index 260d11333..ab6df0343 100644
--- a/test/multiple_ep/test_python_env_system.py
+++ b/test/multiple_ep/test_python_env_system.py
@@ -7,6 +7,7 @@
 
 import pytest
 
+from olive.common.constants import OS
 from olive.systems.system_config import PythonEnvironmentTargetUserConfig, SystemConfig
 
 # pylint: disable=attribute-defined-outside-init
@@ -39,7 +40,7 @@ def test_run_pass_evaluate_windows(self, tmp_path):
         assert dml_res.metrics.value.__root__
         assert openvino_res.metrics.value.__root__
 
-    @pytest.mark.skipif(platform.system() == "Windows", reason="Test for Linux only")
+    @pytest.mark.skipif(platform.system() == OS.WINDOWS, reason="Test for Linux only")
     def test_run_pass_evaluate_linux(self, tmp_path):
         # use the olive managed python environment as the test environment
 
diff --git a/test/unit_test/passes/inc/test_inc_quantization.py b/test/unit_test/passes/inc/test_inc_quantization.py
index f3524143c..7dcaaeb1b 100644
--- a/test/unit_test/passes/inc/test_inc_quantization.py
+++ b/test/unit_test/passes/inc/test_inc_quantization.py
@@ -11,6 +11,7 @@
 from torchvision import transforms
 from torchvision.datasets import CIFAR10
 
+from olive.common.constants import OS
 from olive.data.config import DataConfig
 from olive.model import PyTorchModelHandler
 from olive.passes.olive_pass import create_pass_from_dict
@@ -19,7 +20,7 @@
 
 
 @pytest.mark.skipif(
-    platform.system() == "Windows", reason="Skip test on Windows. neural-compressor import is hanging on Windows."
+    platform.system() == OS.WINDOWS, reason="Skip test on Windows. neural-compressor import is hanging on Windows."
 )
 def test_inc_quantization(tmp_path):
     ov_model = get_onnx_model(tmp_path)
@@ -64,7 +65,7 @@ def test_inc_quantization(tmp_path):
 
 
 @pytest.mark.skipif(
-    platform.system() == "Windows", reason="Skip test on Windows. neural-compressor import is hanging on Windows."
+    platform.system() == OS.WINDOWS, reason="Skip test on Windows. neural-compressor import is hanging on Windows."
 )
 def test_inc_weight_only_quantization(tmp_path):
     ov_model = get_onnx_model(tmp_path)
@@ -95,7 +96,7 @@ def test_inc_weight_only_quantization(tmp_path):
 
 
 @pytest.mark.skipif(
-    platform.system() == "Windows", reason="Skip test on Windows. neural-compressor import is hanging on Windows."
+    platform.system() == OS.WINDOWS, reason="Skip test on Windows. neural-compressor import is hanging on Windows."
 )
 @patch.dict("neural_compressor.quantization.STRATEGIES", {"auto": MagicMock()})
 @patch("olive.passes.onnx.inc_quantization.model_proto_to_olive_model")
diff --git a/test/unit_test/passes/onnx/test_conversion.py b/test/unit_test/passes/onnx/test_conversion.py
index 066eb5f8a..8e7441322 100644
--- a/test/unit_test/passes/onnx/test_conversion.py
+++ b/test/unit_test/passes/onnx/test_conversion.py
@@ -18,6 +18,7 @@
 import pytest
 import torch
 
+from olive.common.constants import OS
 from olive.model import PyTorchModelHandler
 from olive.passes.olive_pass import create_pass_from_dict
 from olive.passes.onnx.conversion import OnnxConversion, OnnxOpVersionConversion
@@ -38,7 +39,7 @@ def test_onnx_conversion_pass(input_model, tmp_path):
 
 
 @pytest.mark.skipif(
-    platform.system() == "Windows" or not torch.cuda.is_available(),
+    platform.system() == OS.WINDOWS or not torch.cuda.is_available(),
     reason="bitsandbytes requires Linux GPU.",
 )
 @pytest.mark.parametrize("add_quantized_modules", [True, False])
diff --git a/test/unit_test/passes/pytorch/test_lora.py b/test/unit_test/passes/pytorch/test_lora.py
index 7ab20791a..c5b194b68 100644
--- a/test/unit_test/passes/pytorch/test_lora.py
+++ b/test/unit_test/passes/pytorch/test_lora.py
@@ -12,6 +12,7 @@
 import pytest
 import torch
 
+from olive.common.constants import OS
 from olive.data.template import huggingface_data_config_template
 from olive.model import PyTorchModelHandler
 from olive.passes.olive_pass import create_pass_from_dict
@@ -83,7 +84,7 @@ def test_lora(tmp_path):
 
 
 @pytest.mark.skipif(
-    platform.system() == "Windows" or not torch.cuda.is_available(),
+    platform.system() == OS.WINDOWS or not torch.cuda.is_available(),
     reason="bitsandbytes requires Linux GPU.",
 )
 def test_qlora(tmp_path):
@@ -96,7 +97,7 @@ def test_qlora(tmp_path):
 
 
 @pytest.mark.skipif(
-    platform.system() == "Windows" or not torch.cuda.is_available(),
+    platform.system() == OS.WINDOWS or not torch.cuda.is_available(),
     reason="bitsandbytes requires Linux GPU.",
 )
 def test_loftq(tmp_path):
diff --git a/test/unit_test/passes/qnn/test_qnn_conversion.py b/test/unit_test/passes/qnn/test_qnn_conversion.py
index 572d48e76..d56ceea85 100644
--- a/test/unit_test/passes/qnn/test_qnn_conversion.py
+++ b/test/unit_test/passes/qnn/test_qnn_conversion.py
@@ -4,6 +4,7 @@
 
 import pytest
 
+from olive.common.constants import OS
 from olive.passes.olive_pass import create_pass_from_dict
 from olive.passes.qnn.conversion import QNNConversion
 
@@ -27,7 +28,7 @@ def test_qnn_conversion_cmd(mocked_qnn_sdk_runner, config, tmp_path):
     mocked_qnn_sdk_runner.return_value.sdk_env.target_arch = "x86_64"
     p.run(input_model, None, tmp_path)
     converter_program = ["qnn-onnx-converter"]
-    if platform.system() == "Windows":
+    if platform.system() == OS.WINDOWS:
         converter_program = ["python", "sdk_root_path\\bin\\x86_64\\qnn-onnx-converter"]
 
     expected_cmd_list = [
diff --git a/test/unit_test/snpe/test_adb_run.py b/test/unit_test/snpe/test_adb_run.py
index 1453386f1..28137b00c 100644
--- a/test/unit_test/snpe/test_adb_run.py
+++ b/test/unit_test/snpe/test_adb_run.py
@@ -11,6 +11,7 @@
 
 import pytest
 
+from olive.common.constants import OS
 from olive.platform_sdk.qualcomm.runner import SDKRunner
 from olive.platform_sdk.qualcomm.snpe.utils.adb import run_adb_command
 
@@ -35,7 +36,7 @@ def test_run_adb_command(mock_run_subprocess, android_target):
 
 
 def test_run_snpe_command():
-    if platform.system() == "Windows":
+    if platform.system() == OS.WINDOWS:
         os.environ["SNPE_ROOT"] = "C:\\snpe"
         target_arch = "x86_64-windows-msvc"
     else:
@@ -51,7 +52,7 @@ def test_run_snpe_command():
         mock_run_subprocess.return_value = CompletedProcess(None, returncode=0, stdout=b"stdout", stderr=b"stderr")
         runner = SDKRunner(platform="SNPE")
         stdout, _ = runner.run(cmd="snpe-net-run --container xxxx")
-        if platform.system() == "Linux":
+        if platform.system() == OS.LINUX:
             env = {
                 "LD_LIBRARY_PATH": "/snpe/lib/x86_64-linux-clang",
                 "PATH": f"/snpe/bin/x86_64-linux-clang:/usr/bin:{os.environ['PATH']}",
diff --git a/test/unit_test/systems/isolated_ort/test_isolated_ort_system.py b/test/unit_test/systems/isolated_ort/test_isolated_ort_system.py
index fb92fff66..7502540cb 100644
--- a/test/unit_test/systems/isolated_ort/test_isolated_ort_system.py
+++ b/test/unit_test/systems/isolated_ort/test_isolated_ort_system.py
@@ -16,6 +16,7 @@
 import pytest
 import torch
 
+from olive.common.constants import OS
 from olive.common.utils import run_subprocess
 from olive.constants import Framework
 from olive.evaluator.metric import AccuracySubType, LatencySubType
@@ -107,7 +108,7 @@ def setup(self, tmp_path):
         venv_path = tmp_path / "venv"
         venv.create(venv_path, with_pip=True)
         # python path
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             python_environment_path = f"{venv_path}/Scripts"
         else:
             python_environment_path = f"{venv_path}/bin"
diff --git a/test/unit_test/systems/python_environment/test_python_environment_system.py b/test/unit_test/systems/python_environment/test_python_environment_system.py
index e1911ea6e..e37f75d41 100644
--- a/test/unit_test/systems/python_environment/test_python_environment_system.py
+++ b/test/unit_test/systems/python_environment/test_python_environment_system.py
@@ -19,6 +19,7 @@
 
 import pytest
 
+from olive.common.constants import OS
 from olive.common.utils import run_subprocess
 from olive.evaluator.metric_result import MetricResult, joint_metric_key
 from olive.hardware import DEFAULT_CPU_ACCELERATOR
@@ -39,7 +40,7 @@ def setup(self, tmp_path):
         venv_path = tmp_path / "venv"
         venv.create(venv_path, with_pip=True)
         # python path
-        if platform.system() == "Windows":
+        if platform.system() == OS.WINDOWS:
             self.python_environment_path = Path(venv_path) / "Scripts"
         else:
             self.python_environment_path = Path(venv_path) / "bin"
diff --git a/test/unit_test/test_cache.py b/test/unit_test/test_cache.py
index 02307f4d8..f496b7216 100644
--- a/test/unit_test/test_cache.py
+++ b/test/unit_test/test_cache.py
@@ -12,6 +12,7 @@
 import pytest
 
 from olive.cache import clean_pass_run_cache, create_cache, download_resource, get_cache_sub_dirs, save_model
+from olive.common.constants import OS
 from olive.resource_path import AzureMLModel
 
 
@@ -47,7 +48,7 @@ def test_clean_pass_run_cache(self, model_path):
         model_cache_file_path = str((model_cache_dir / "0_p(･◡･)p.json").resolve())
         with open(model_cache_file_path, "w") as model_cache_file:
             model_data = f'{{"model_path": "{model_p}"}}'
-            if platform.system() == "Windows":
+            if platform.system() == OS.WINDOWS:
                 model_data = model_data.replace("\\", "//")
             model_cache_file.write(model_data)
 
diff --git a/test/unit_test/workflows/test_setup.py b/test/unit_test/workflows/test_setup.py
index 90ac891e3..d699c36d0 100644
--- a/test/unit_test/workflows/test_setup.py
+++ b/test/unit_test/workflows/test_setup.py
@@ -10,6 +10,7 @@
 
 import pytest
 
+from olive.common.constants import OS
 from olive.common.utils import run_subprocess
 
 # pylint: disable=redefined-outer-name
@@ -25,7 +26,7 @@ def post_setup(self, context) -> None:
 
 @pytest.fixture()
 def config_json(tmp_path):
-    if platform.system() == "Windows":
+    if platform.system() == OS.WINDOWS:
         ep = "DmlExecutionProvider"
     else:
         ep = "CUDAExecutionProvider"
@@ -45,7 +46,7 @@ def test_dependency_setup(tmp_path, config_json):
     builder = DependencySetupEnvBuilder(with_pip=True)
     builder.create(str(tmp_path))
 
-    if platform.system() == "Windows":
+    if platform.system() == OS.WINDOWS:
         python_path = tmp_path / "Scripts" / "python"
         ort_extra = "onnxruntime-directml"
     else: