diff --git a/code/modules/research/designs/prosfab_designs.dm b/code/modules/research/designs/prosfab_designs.dm
index 70959293a27b..5d3b3caac411 100644
--- a/code/modules/research/designs/prosfab_designs.dm
+++ b/code/modules/research/designs/prosfab_designs.dm
@@ -13,6 +13,8 @@
 	if(istype(fabricator, /obj/machinery/mecha_part_fabricator/pros))
 		var/obj/machinery/mecha_part_fabricator/pros/prosfab = fabricator
 		var/obj/item/organ/O = new build_path(where)
+		if(!istype(O))
+			return O
 		if(prosfab.manufacturer)
 			var/datum/robolimb/manf = GLOB.all_robolimbs[prosfab.manufacturer]