diff --git a/criterion/cache.py b/criterion/cache.py
index cf8d8fb..521bf8e 100644
--- a/criterion/cache.py
+++ b/criterion/cache.py
@@ -33,7 +33,7 @@ def archivePosters(init=False):
         imdbId = data['imdbId']
         try:
             m = IdMapping.objects.get(criterion_id=criterionId)
-            if imdbId and imdb != m.imdb_id:
+            if imdbId and imdbId != m.imdb_id:
                 m.imdb_id = imdbId
                 m.save()
         except IdMapping.DoesNotExist: