diff --git a/code/modules/research/protolathe.dm b/code/modules/research/protolathe.dm
index 197ac1d7253..9e1a31e84db 100644
--- a/code/modules/research/protolathe.dm
+++ b/code/modules/research/protolathe.dm
@@ -119,11 +119,12 @@ Note: Must be placed west/left of and R&D console to function.
 	if(!amount_inserted)
 		return 1
 	else
+		var/stack_name = stack.name
 		busy = 1
 		use_power(max(1000, (MINERAL_MATERIAL_AMOUNT*amount_inserted/10)))
 		user << "<span class='notice'>You add [amount_inserted] sheets to the [src.name].</span>"
-		overlays += "protolathe_[stack.name]"
+		overlays += "protolathe_[stack_name]"
 		sleep(10)
-		overlays -= "protolathe_[stack.name]"
+		overlays -= "protolathe_[stack_name]"
 		busy = 0
 	updateUsrDialog()