diff --git a/oyster/scripts/signal.py b/oyster/scripts/signal.py
index 9284d77..c6a6608 100644
--- a/oyster/scripts/signal.py
+++ b/oyster/scripts/signal.py
@@ -15,7 +15,9 @@ def main():
 
     args = parser.parse_args()
 
-    docs = kernel.db.tracked.find({'doc_class': args.doc_class}, timeout=False)
+    docs = kernel.db.tracked.find({'doc_class': args.doc_class,
+                                   'versions': {'$ne': []}
+                                  }, timeout=False)
     print '%s docs in %s' % (docs.count(), args.doc_class)
 
     for doc in docs: