diff --git a/src/main/java/refinedstorage/item/ItemUpgrade.java b/src/main/java/refinedstorage/item/ItemUpgrade.java
index 7557796c6..0872ecbf1 100755
--- a/src/main/java/refinedstorage/item/ItemUpgrade.java
+++ b/src/main/java/refinedstorage/item/ItemUpgrade.java
@@ -16,6 +16,7 @@ public class ItemUpgrade extends ItemBase {
 
         setHasSubtypes(true);
         setMaxDamage(0);
+        setMaxStackSize(1);
     }
 
     @Override