diff --git a/flask/ext/__init__.py b/flask/ext/__init__.py
index 078e7dbd..14c8d8d4 100644
--- a/flask/ext/__init__.py
+++ b/flask/ext/__init__.py
@@ -58,7 +58,8 @@ class _ExtensionImporter(object):
             except ImportError:
                 continue
             module = modules[fullname] = modules[realname]
-            setattr(modules[__name__], modname, module)
+            if '.' not in modname:
+                setattr(modules[__name__], modname, module)
             return module
         raise ImportError(fullname)
 
diff --git a/flask/testsuite/ext.py b/flask/testsuite/ext.py
index 41bbabeb..a64b9bd2 100644
--- a/flask/testsuite/ext.py
+++ b/flask/testsuite/ext.py
@@ -31,6 +31,11 @@ class ExtImportHookTestCase(FlaskTestCase):
                 import_hooks += 1
         self.assert_equal(import_hooks, 1)
 
+    def teardown(self):
+        from flask import ext
+        for key in ext.__dict__:
+            self.assert_('.' not in key)
+
     def test_flaskext_new_simple_import_normal(self):
         from flask.ext.newext_simple import ext_id
         self.assert_equal(ext_id, 'newext_simple')