diff --git a/mitogen/core.py b/mitogen/core.py
index 859b0689..080c58ef 100644
--- a/mitogen/core.py
+++ b/mitogen/core.py
@@ -263,7 +263,8 @@ class CallError(Error, object):
             Error.__init__(self, fmt, *args)
         else:
             e = fmt
-            fmt = '%s.%s: %s' % (type(e).__module__, type(e).__name__, e)
+            cls = e.__class__
+            fmt = '%s.%s: %s' % (cls.__module__, cls.__name__, e)
             tb = sys.exc_info()[2]
             if tb:
                 fmt += '\n'
diff --git a/tests/call_error_test.py b/tests/call_error_test.py
index baebd1eb..72df95b7 100644
--- a/tests/call_error_test.py
+++ b/tests/call_error_test.py
@@ -31,9 +31,10 @@ class ConstructorTest(testlib.TestCase):
     def test_form_base_exc(self):
         ve = SystemExit('eek')
         e = self.klass(ve)
+        cls = ve.__class__
         self.assertEquals(e.args[0],
             # varies across 2/3.
-            '%s.%s: eek' % (type(ve).__module__, type(ve).__name__))
+            '%s.%s: eek' % (cls.__module__, cls.__name__))
         self.assertTrue(isinstance(e.args[0], mitogen.core.UnicodeType))
 
     def test_from_exc_tb(self):