diff --git a/nose_parameterized/parameterized.py b/nose_parameterized/parameterized.py
index cb2398f..4b838fc 100644
--- a/nose_parameterized/parameterized.py
+++ b/nose_parameterized/parameterized.py
@@ -161,8 +161,8 @@ class parameterized(object):
         if len(stack) <= 4:
             return []
         frame = stack[4]
-        code_context = frame[4][0].strip()
-        if not code_context.startswith("class "):
+        code_context = frame[4] and frame[4][0].strip()
+        if not (code_context and code_context.startswith("class ")):
             return []
         _, parents = code_context.split("(", 1)
         parents, _ = parents.rsplit(")", 1)
diff --git a/nose_parameterized/test.py b/nose_parameterized/test.py
index bf6256e..ee99ebb 100644
--- a/nose_parameterized/test.py
+++ b/nose_parameterized/test.py
@@ -50,7 +50,7 @@ def test_warns_when_using_parameterized_with_TestCase():
     try:
         class TestTestCaseWarnsOnBadUseOfParameterized(TestCase):
             @parameterized([42])
-            def test_should_throw_error(self, foo):
+            def test_in_subclass_of_TestCase(self, foo):
                 pass
     except Exception as e:
         assert_contains(str(e), "parameterized.expand")
diff --git a/tox.ini b/tox.ini
index f685d42..156489e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist=py26,py27,py32
+envlist=py26,py27,py32,py33
 
 [testenv]
 deps=nose==1.2.1