diff --git a/code/game/objects/items/stacks/stack.dm b/code/game/objects/items/stacks/stack.dm
index b71b1a22073..c7b05840f9f 100644
--- a/code/game/objects/items/stacks/stack.dm
+++ b/code/game/objects/items/stacks/stack.dm
@@ -225,6 +225,8 @@
 		if(O)
 			O.setDir(usr.dir)
 		use(R.req_amount * multiplier)
+		for(var/i in custom_materials)
+			custom_materials[i] = amount * mats_per_stack
 	
 		if(R.applies_mats && custom_materials && custom_materials.len)
 			var/list/used_materials = list()