diff --git a/migrate/versioning/version.py b/migrate/versioning/version.py
index 18dc00a..d0842e3 100644
--- a/migrate/versioning/version.py
+++ b/migrate/versioning/version.py
@@ -161,7 +161,7 @@ class Version(object):
         # TODO: maybe add force Python parameter?
         ret = self.python
 
-        assert ret is not None,
+        assert ret is not None, \
             "There is no script for %d version" % self.version
         return ret