diff --git a/code/modules/assembly/proximity.dm b/code/modules/assembly/proximity.dm
index cfc46a86a5..2b71743416 100644
--- a/code/modules/assembly/proximity.dm
+++ b/code/modules/assembly/proximity.dm
@@ -40,6 +40,9 @@
 
 
 	HasProximity(atom/movable/AM as mob|obj)
+		if(!istype(AM))
+			log_debug("DEBUG: HasProximity called with [AM] on [src] ([usr]).")
+			return
 		if (istype(AM, /obj/effect/beam))	return
 		if (AM.move_speed < 12)	sense()
 		return