diff --git a/requirements-openvino.txt b/requirements-openvino.txt
index e555d52572541..e32c76fb0db21 100644
--- a/requirements-openvino.txt
+++ b/requirements-openvino.txt
@@ -4,6 +4,6 @@
 # OpenVINO dependencies
 torch >= 2.1.2
 openvino ~= 2024.3.0.dev
-optimum-intel[openvino] >= 1.17.2
+optimum-intel[openvino] >= 1.18.1
 
 triton >= 2.2.0  # FIXME(woosuk): This is a hack to avoid import error.
diff --git a/vllm/engine/llm_engine.py b/vllm/engine/llm_engine.py
index d354218cf16ea..622221d2dd13e 100644
--- a/vllm/engine/llm_engine.py
+++ b/vllm/engine/llm_engine.py
@@ -284,7 +284,7 @@ def __init__(
                     "quantization":
                     model_config.quantization,
                     "kv_cache_dtype":
-                    cache_config.cache_dtype,
+                    str(cache_config.cache_dtype),
 
                     # Feature flags
                     "enable_lora":