diff --git a/IPython/core/completerlib.py b/IPython/core/completerlib.py
index 466041f..4a30980 100644
--- a/IPython/core/completerlib.py
+++ b/IPython/core/completerlib.py
@@ -80,10 +80,15 @@ def module_list(path):
     pjoin = os.path.join
     basename = os.path.basename
 
+    def is_importable_file(path):
+        """Returns True if the provided path is a valid importable module"""
+        name, extension = os.path.splitext( path )
+        return import_re.match(path) and py3compat.isidentifier(name)
+
     # Now find actual path matches for packages or modules
     folder_list = [p for p in folder_list
                    if isfile(pjoin(path, p,'__init__.py'))
-                   or import_re.match(p) ]
+                   or is_importable_file(p) ]
 
     return [basename(p).split('.')[0] for p in folder_list]
 
diff --git a/IPython/core/tests/test_completerlib.py b/IPython/core/tests/test_completerlib.py
index b442eb9..745f838 100644
--- a/IPython/core/tests/test_completerlib.py
+++ b/IPython/core/tests/test_completerlib.py
@@ -76,4 +76,5 @@ class Test_magic_run_completer(unittest.TestCase):
                 open(filename, 'w').close()
 
             s = set( module_completion('import foo') )
-            self.assertFalse( s.intersection(invalid_module_names) )
+            intersection = s.intersection(invalid_module_names)
+            self.assertFalse(intersection, intersection)