1 files changed, 11 insertions, 1 deletions
diff --git a/Tools/scripts/generate_stdlib_module_names.py b/Tools/scripts/generate_stdlib_module_names.py
index 716a6d4b7a..325ae202b1 100644
--- a/Tools/scripts/generate_stdlib_module_names.py
+++ b/Tools/scripts/generate_stdlib_module_names.py
@@ -117,9 +117,19 @@ def list_frozen(names):
         cmd = ' '.join(args)
         print(f"{cmd} failed with exitcode {exitcode}")
         sys.exit(exitcode)
+    submodules = set()
     for line in proc.stdout.splitlines():
         name = line.strip()
-        names.add(name)
+        if '.' in name:
+            submodules.add(name)
+        else:
+            names.add(name)
+    # Make sure all frozen submodules have a known parent.
+    for name in list(submodules):
+        if name.partition('.')[0] in names:
+            submodules.remove(name)
+    if submodules:
+        raise Exception(f'unexpected frozen submodules: {sorted(submodules)}')
 
 
 def list_modules():