diff --git a/Lib/rlcompleter.py b/Lib/rlcompleter.py
--- a/Lib/rlcompleter.py
+++ b/Lib/rlcompleter.py
@@ -68,16 +68,22 @@ class Completer:
 
         This is called successively with state == 0, 1, 2, ... until it
         returns None.  The completion should begin with 'text'.
 
         """
         if self.use_main_ns:
             self.namespace = __main__.__dict__
 
+        if not text.strip():
+            if state == 0:
+                return '\t'
+            else:
+                return None
+
         if state == 0:
             if "." in text:
                 self.matches = self.attr_matches(text)
             else:
                 self.matches = self.global_matches(text)
         try:
             return self.matches[state]
         except IndexError:
diff --git a/Lib/test/test_rlcompleter.py b/Lib/test/test_rlcompleter.py
--- a/Lib/test/test_rlcompleter.py
+++ b/Lib/test/test_rlcompleter.py
@@ -60,14 +60,19 @@ class TestRlcompleter(unittest.TestCase)
 
         CompleteMe.me = CompleteMe
         self.assertEqual(self.completer.attr_matches('CompleteMe.me.me.sp'),
                          ['CompleteMe.me.me.spam'])
         self.assertEqual(self.completer.attr_matches('egg.s'),
                          ['egg.{}('.format(x) for x in dir(str)
                           if x.startswith('s')])
 
-def test_main():
-    support.run_unittest(TestRlcompleter)
+    def test_complete(self):
+        completer = rlcompleter.Completer()
+        self.assertEqual(completer.complete('', 0), '\t')
+        self.assertEqual(completer.complete('a', 0), 'and')
+        self.assertEqual(completer.complete('a', 1), 'as')
+        self.assertEqual(completer.complete('as', 2), 'assert')
+        self.assertEqual(completer.complete('an', 0), 'and')
 
 
 if __name__ == '__main__':
-    test_main()
+    unittest.main()