diff --git a/Source/DataSources/StaticGroundPolylinePerMaterialBatch.js b/Source/DataSources/StaticGroundPolylinePerMaterialBatch.js
index f5df9d4d540e..52db90df13d9 100644
--- a/Source/DataSources/StaticGroundPolylinePerMaterialBatch.js
+++ b/Source/DataSources/StaticGroundPolylinePerMaterialBatch.js
@@ -348,7 +348,7 @@ define([
         }
 
         var isUpdated = true;
-        for (i = 0; i < length; i++) {
+        for (i = 0; i < items.length; i++) {
             isUpdated = items[i].update(time) && isUpdated;
         }
         return isUpdated;