diff --git a/code/game/objects/items/stacks/stack.dm b/code/game/objects/items/stacks/stack.dm
index 7cef6094ea..a732416dfb 100644
--- a/code/game/objects/items/stacks/stack.dm
+++ b/code/game/objects/items/stacks/stack.dm
@@ -296,7 +296,7 @@
 
 
 /obj/item/stack/attackby(obj/item/W, mob/user, params)
-	if(istype(W, merge_type))
+	if(istype(W, merge_type) && amount < max_amount)
 		var/obj/item/stack/S = W
 		merge(S)
 		to_chat(user, "<span class='notice'>Your [S.name] stack now contains [S.get_amount()] [S.singular_name]\s.</span>")