diff --git a/code/game/machinery/firealarm.dm b/code/game/machinery/firealarm.dm
index 8f7fce8e3e..51cd9de2d1 100644
--- a/code/game/machinery/firealarm.dm
+++ b/code/game/machinery/firealarm.dm
@@ -256,6 +256,21 @@
 					return
 	return ..()
 
+/obj/machinery/firealarm/rcd_vals(mob/user, obj/item/construction/rcd/the_rcd)
+	if((buildstage == 0) && (the_rcd.upgrade & RCD_UPGRADE_SIMPLE_CIRCUITS))
+		return list("mode" = RCD_UPGRADE_SIMPLE_CIRCUITS, "delay" = 20, "cost" = 1)
+	return FALSE
+
+/obj/machinery/firealarm/rcd_act(mob/user, obj/item/construction/rcd/the_rcd, passed_mode)
+	switch(passed_mode)
+		if(RCD_UPGRADE_SIMPLE_CIRCUITS)
+			user.visible_message("<span class='notice'>[user] fabricates a circuit and places it into [src].</span>", \
+			"<span class='notice'>You adapt a fire alarm circuit and slot it into the assembly.</span>")
+			buildstage = 1
+			update_icon()
+			return TRUE
+	return FALSE
+
 /obj/machinery/firealarm/take_damage(damage_amount, damage_type = BRUTE, damage_flag = 0, sound_effect = 1, attack_dir)
 	. = ..()
 	if(.) //damage received