diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 473d548e..3d81b13d 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -13,7 +13,7 @@ jobs:
           - { python-version: 3.8, os: ubuntu-latest }
           - { python-version: 3.7, os: ubuntu-latest }
           - { python-version: 3.6, os: ubuntu-latest }
-          # - { python-version: 3.8, os: windows-latest }
+          - { python-version: 3.8, os: windows-latest }
           - { python-version: 3.8, os: macos-latest }
 
     steps:
@@ -21,7 +21,7 @@ jobs:
       - uses: actions/setup-python@v2.1.1
         with:
           python-version: ${{ matrix.python-version }}
-          # architecture: x64
+          architecture: x64
       - run: pip install nox==2020.5.24
       - run: pip install poetry==1.0.9
       - run: nox
diff --git a/noxfile.py b/noxfile.py
index a4cfa068..27d3450e 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -1,5 +1,6 @@
 """Nox Sessions."""
 import tempfile
+from pathlib import Path
 
 import nox
 
@@ -9,23 +10,24 @@
 
 def install_with_constraints(session, *args, **kwargs):
     """Install packages constrained by Poetry's lock file."""
-    with tempfile.NamedTemporaryFile() as requirements:
+    with tempfile.TemporaryDirectory() as directory:
+        requirements = Path(directory) / "requirements.txt"
         session.run(
             "poetry",
             "export",
             "--dev",
             "--format=requirements.txt",
-            f"--output={requirements.name}",
+            f"--output={requirements}",
             external=True,
         )
-        session.install(f"--constraint={requirements.name}", *args, **kwargs)
+        session.install(f"--constraint={requirements}", *args, **kwargs)
 
 
 @nox.session()
 def tests(session):
     """Run the test suite."""
     args = session.posargs or ["--cov", "-m", "not e2e"]
-    session.run("poetry", "install", "--no-dev", external=True)
+    session.run("poetry", "install", external=True)
     install_with_constraints(session, "coverage[toml]", "pytest", "pytest-cov")
     session.run("pytest", *args)
 
@@ -64,18 +66,18 @@ def black(session):
 @nox.session()
 def safety(session):
     """Scan dependencies for insecure packages."""
-    with tempfile.NamedTemporaryFile() as requirements:
+    with tempfile.TemporaryDirectory() as directory:
+        requirements = Path(directory) / "requirements.txt"
         session.run(
             "poetry",
             "export",
             "--dev",
             "--format=requirements.txt",
-            "--without-hashes",
-            f"--output={requirements.name}",
+            f"--output={requirements}",
             external=True,
         )
         install_with_constraints(session, "safety")
-        session.run("safety", "check", f"--file={requirements.name}", "--full-report")
+        session.run("safety", "check", f"--file={requirements}", "--full-report")
 
 
 @nox.session()
diff --git a/tests/test_core.py b/tests/test_core.py
index 63e9d18f..76730026 100644
--- a/tests/test_core.py
+++ b/tests/test_core.py
@@ -1,5 +1,6 @@
 import pytest
 
+import matplotlib
 import matplotlib.pyplot as plt
 import numpy as np
 from matplotlib.axes import Axes
@@ -7,6 +8,9 @@
 
 import seaborn_image as isns
 
+matplotlib.use("AGG")  # use non-interactive backend for tests
+
+
 data = np.random.random(2500).reshape((50, 50))
 
 
diff --git a/tests/test_filters.py b/tests/test_filters.py
index b975237c..00a4d6e9 100644
--- a/tests/test_filters.py
+++ b/tests/test_filters.py
@@ -1,5 +1,6 @@
 import pytest
 
+import matplotlib
 import matplotlib.pyplot as plt
 import numpy as np
 import scipy.ndimage as ndi
@@ -8,6 +9,9 @@
 
 import seaborn_image as isns
 
+matplotlib.use("AGG")  # use non-interactive backend for tests
+
+
 data = np.random.random(2500).reshape((50, 50))
 filter_list = ["sobel", "gaussian", "median", "max", "diff_of_gaussians"]
 
@@ -17,9 +21,7 @@ def test_filter_not_implemented():
         isns.filterplot(data, filter="not-implemented-filter")
 
 
-@pytest.mark.parametrize(
-    "filter", [["gaussian"], ndi.gaussian_filter, None]
-)
+@pytest.mark.parametrize("filter", [["gaussian"], ndi.gaussian_filter, None])
 def test_filter_types(filter):
     with pytest.raises(TypeError):
         isns.filterplot(data, filter=filter)
diff --git a/tests/test_general.py b/tests/test_general.py
index ea1f4bca..f48d151f 100644
--- a/tests/test_general.py
+++ b/tests/test_general.py
@@ -1,5 +1,6 @@
 import pytest
 
+import matplotlib
 import matplotlib.pyplot as plt
 import numpy as np
 from matplotlib.axes import Axes
@@ -7,6 +8,9 @@
 
 import seaborn_image as isns
 
+matplotlib.use("AGG")  # use non-interactive backend for tests
+
+
 data = np.random.random(2500).reshape((50, 50))
 
 
@@ -120,7 +124,15 @@ def test_imghist_return():
 @pytest.mark.parametrize("title_fontdict", [{"fontsize": 20}, None])
 @pytest.mark.parametrize("describe", [True, False])
 def test_imghist_w_all_valid_inputs(
-    cmap, bins, cbar, cbar_label, cbar_fontdict, showticks, title, title_fontdict, describe
+    cmap,
+    bins,
+    cbar,
+    cbar_label,
+    cbar_fontdict,
+    showticks,
+    title,
+    title_fontdict,
+    describe,
 ):
     f, axes, cax = isns.imghist(
         data,