diff --git a/tests/unit/forklift/test_legacy.py b/tests/unit/forklift/test_legacy.py
index 688fa995ef35..ed93026db84a 100644
--- a/tests/unit/forklift/test_legacy.py
+++ b/tests/unit/forklift/test_legacy.py
@@ -882,6 +882,11 @@ def test_fails_with_invalid_names(self, pyramid_config, db_request, name):
                                       "main", "future", "al", "uU", "test",
                                       "encodings.utf_8_sig",
                                       "distutils.command.build_clib",
+                                      "xmlrpc", "xmlrpc.server",
+                                      "xml.etree", "xml.etree.ElementTree",
+                                      "xml.parsers", "xml.parsers.expat",
+                                      "xml.parsers.expat.errors",
+                                      "encodings.idna", "encodings",
                                       "CGIHTTPServer", "cgihttpserver"])
     def test_fails_with_stdlib_names(self, pyramid_config, db_request, name):
         pyramid_config.testing_securitypolicy(userid=1)
diff --git a/warehouse/forklift/legacy.py b/warehouse/forklift/legacy.py
index 092a3acd2ef7..cb0d71eff75f 100644
--- a/warehouse/forklift/legacy.py
+++ b/warehouse/forklift/legacy.py
@@ -52,10 +52,19 @@
 
 PATH_HASHER = "blake2_256"
 
+
+def namespace_stdlib_list(module_list):
+    for module_name in module_list:
+        parts = module_name.split('.')
+        for i, part in enumerate(parts):
+            yield '.'.join(parts[:i + 1])
+
+
 STDLIB_PROHIBITTED = {
     packaging.utils.canonicalize_name(s.rstrip('-_.').lstrip('-_.'))
-    for s in chain.from_iterable(stdlib_list.stdlib_list(version)
-                                 for version in stdlib_list.short_versions)
+    for s in chain.from_iterable(
+        namespace_stdlib_list(stdlib_list.stdlib_list(version))
+        for version in stdlib_list.short_versions)
 }
 
 # Wheel platform checking