diff --git a/src/subtitles-octopus.js b/src/subtitles-octopus.js
index f168a639..3b8f28e2 100644
--- a/src/subtitles-octopus.js
+++ b/src/subtitles-octopus.js
@@ -292,7 +292,7 @@ var SubtitlesOctopus = function (options) {
             }
         }
 
-        var removed = retainedItems.length < self.renderedItems;
+        var removed = retainedItems.length < self.renderedItems.length;
         self.renderedItems = retainedItems;
         return removed;
     }