diff --git a/tests/imagespecs.py b/tests/imagespecs.py
index 536db7a..8a69975 100644
--- a/tests/imagespecs.py
+++ b/tests/imagespecs.py
@@ -5,4 +5,4 @@ class TestSpec(ImageSpec):
     pass
 
 
-register.spec(TestSpec, 'testspec')
+register.spec('testspec', TestSpec)