diff --git a/.ci/scripts/wheel/test_clean_install.py b/.ci/scripts/wheel/test_clean_install.py
index 65943277324..13840ed8807 100644
--- a/.ci/scripts/wheel/test_clean_install.py
+++ b/.ci/scripts/wheel/test_clean_install.py
@@ -215,10 +215,10 @@ def run_tests(work_dir: Path) -> None:
 
 
 # Reads its arguments from stdin, blocks the named modules, then imports. A blocked module
-# raises ModuleNotFoundError exactly as it would be absent, so the traceback shows the import
-# chain that wanted it.
+# behaves like a missing one to import and find_spec, so the traceback shows the import chain
+# that wanted it.
 _IMPORT_PROBE = """
-import importlib.abc, importlib.util, json, os, sys
+import importlib, json, os, sys
 
 # Drop the working directory, which `python -c` puts first. The equivalent flag, -P, is only
 # available from 3.11.
@@ -229,19 +229,23 @@ def run_tests(work_dir: Path) -> None:
 request = json.load(sys.stdin)
 blocked = set(request["blocked"])
 
-
-class _Blocker(importlib.abc.MetaPathFinder):
-    def find_spec(self, fullname, path=None, target=None):
-        if fullname.split(".")[0] in blocked:
-            raise ModuleNotFoundError(
-                f"No module named {fullname!r} (not declared by the executorch wheel)",
-                name=fullname,
-            )
-        return None
-
-
-sys.meta_path.insert(0, _Blocker())
-importlib.import_module(request["module"])
+# A None entry in sys.modules makes an import raise ModuleNotFoundError while
+# importlib.util.find_spec returns None, which is how a missing package behaves. A finder that
+# raises from find_spec instead breaks code that probes for optional packages, such as
+# torch._dynamo, which looks up hypothesis that way.
+for name in blocked:
+    sys.modules[name] = None
+
+try:
+    importlib.import_module(request["module"])
+except ModuleNotFoundError as error:
+    package = (error.name or "").split(".")[0]
+    if package in blocked:
+        raise ModuleNotFoundError(
+            f"No module named {package!r} (not declared by the executorch wheel)",
+            name=package,
+        ) from error
+    raise
 """
 
 
diff --git a/requirements-dev.txt b/requirements-dev.txt
index e9575084648..a6f33b6f885 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -21,3 +21,8 @@ pytest-xdist
 pytest-rerunfailures==15.1
 pytest-json-report
 gguf  # For extension/llm/export/test/test_gguf.py (GGUF Q4_K/Q6_K dequant tests).
+# Needed only by tests and development tools, so the executorch package does not depend on them.
+expecttest
+hypothesis
+kgb
+parameterized
diff --git a/setup.py b/setup.py
index c3d73287242..811619321ec 100644
--- a/setup.py
+++ b/setup.py
@@ -1154,15 +1154,11 @@ def _base_dependencies() -> List[str]:
     project's runtime needs.
     """
     return [
-        "expecttest",
         "flatbuffers",
-        "hypothesis",
-        "kgb",
         "mpmath==1.3.0",
         "numpy>=2.0.0; python_version >= '3.10'",
         "packaging",
         "pandas>=2.2.2; python_version >= '3.10'",
-        "parameterized",
         # The Qualcomm backend needs both, on different paths. Any lowering reads the CPU vendor
         # to disable an mkldnn path that crashes on AMD, whether or not an SDK is already set up.
         # Fetching an SDK additionally needs requests, which its downloader imports at module