diff --git a/samples/azure-pack/tests/test-sample.py b/samples/azure-pack/tests/test-sample.py
new file mode 100644
index 0000000..56695b3
--- /dev/null
+++ b/samples/azure-pack/tests/test-sample.py
@@ -0,0 +1,22 @@
+import os, sys
+EXPECT_PREFIX = os.getenv("BUILD_PREFIX")
+print("EXPECT_PREFIX =", EXPECT_PREFIX)
+sys.path.insert(0, os.path.join(EXPECT_PREFIX, "azure-pack"))
+
+
+import azure
+import azure.identity
+
+print("azure.identity.__spec__ =", azure.identity.__spec__)
+assert azure.identity.__spec__.origin.startswith(EXPECT_PREFIX)
+assert type(azure.identity.__spec__.loader).__name__ == "DllPackLoader_azure"
+
+import cryptography
+print("cryptography.__spec__ =", cryptography.__spec__)
+assert cryptography.__spec__.origin.startswith(EXPECT_PREFIX)
+assert type(cryptography.__spec__.loader).__name__ == "DllPackLoader_cryptography"
+
+import cryptography.hazmat.bindings._rust as cryptography_rust
+print("cryptography_rust.__spec__ =", cryptography_rust.__spec__)
+assert cryptography_rust.__spec__.origin.startswith(EXPECT_PREFIX)
+assert type(cryptography_rust.__spec__.loader).__name__ == "ExtensionFileLoader"
diff --git a/tests/test_samples.py b/tests/test_samples.py
index 835f607..bdc9e73 100644
--- a/tests/test_samples.py
+++ b/tests/test_samples.py
@@ -1,3 +1,4 @@
+import importlib.machinery
 import os
 import pytest
 import shutil
@@ -49,6 +50,14 @@ def fresh_copy(sample, tmp_path):
     return TMP
 
 
+def rglob_ext(root):
+    root = Path(root)
+    exts = set()
+    for suffix in importlib.machinery.EXTENSION_SUFFIXES:
+        exts.update(root.rglob(f"*{suffix}"))
+    return exts
+
+
 @all_samples
 def test_sample_build_inplace(sample, tmp_path):
     maybe_skip(sample)
@@ -62,17 +71,25 @@ def test_sample_build_inplace(sample, tmp_path):
             [sys.executable, "-m", "pip", "install", "-r", DIR / "requirements.txt", "--target", PACKAGES],
             env=env,
         )
-        env["PYTHONPATH"] = f"{PACKAGES}{os.pathsep}{env['PYTHONPATH']}"
+        env["PYTHONPATH"] = os.pathsep.join(str(s) for s in [PACKAGES, env["PYTHONPATH"]] if s)
 
     subprocess.check_call(
         [sys.executable, "-m", "pymsbuild"],
         cwd=DIR,
         env=env,
     )
-    modules = {f.relative_to(DIR) for f in DIR.rglob("*.pyd")}
+    modules = {f.relative_to(DIR) for f in rglob_ext(DIR)}
     without_temp = {f for f in modules if f.parts[0] != "build"}
     assert without_temp
 
+    env["BUILD_PREFIX"] = str(DIR)
+    env["PYTHONPATH"] = ""
+    subprocess.check_call(
+        [sys.executable, DIR / "tests/test-sample.py"],
+        cwd=DIR,
+        env=env,
+    )
+
 @all_samples
 def test_sample_sdist(sample, tmp_path):
     maybe_skip(sample)