diff -r 5e05d7d3db9c Lib/inspect.py
--- a/Lib/inspect.py	Sat Mar 01 07:53:28 2014 -0500
+++ b/Lib/inspect.py	Sat Mar 01 11:03:16 2014 -0500
@@ -1208,7 +1208,7 @@
     missing = 0
     for kwarg in kwonlyargs:
         if kwarg not in arg2value:
-            if kwarg in kwonlydefaults:
+            if kwonlydefaults and kwarg in kwonlydefaults:
                 arg2value[kwarg] = kwonlydefaults[kwarg]
             else:
                 missing += 1
diff -r 5e05d7d3db9c Lib/test/test_inspect.py
--- a/Lib/test/test_inspect.py	Sat Mar 01 07:53:28 2014 -0500
+++ b/Lib/test/test_inspect.py	Sat Mar 01 11:03:16 2014 -0500
@@ -1206,6 +1206,19 @@
         self.assertEqualException(f3, '1, 2')
         self.assertEqualException(f3, '1, 2, a=1, b=2')
 
+        # bug in 3.4rc1 tries to iterate over non-existant kwonlydefaults
+        # and raises a TypeError about iteration when it should raise a
+        # TypeError about missing arguments
+        def f5(*, a): pass
+        try:
+            inspect.getcallargs(f5)
+        except TypeError as err:
+            self.assertTrue('missing 1 required keyword-only' in str(err))
+        except:
+            raise
+
+
+
 class TestGetcallargsMethods(TestGetcallargsFunctions):
 
     def setUp(self):