diff --git a/code/__HELPERS/atoms.dm b/code/__HELPERS/atoms.dm
index d86c8623b1b..bbd859e0021 100644
--- a/code/__HELPERS/atoms.dm
+++ b/code/__HELPERS/atoms.dm
@@ -71,3 +71,12 @@
 		if(length(check.contents))
 			atoms |= check.collect_all_atoms_of_type(path, blacklist)
 	return atoms
+/**
+ * 	Proc that returns if selected loc, or atom is within boundaries of playable area. (non-transitional space)
+ */
+/proc/is_location_within_transition_boundaries(atom/loc)
+	return (loc.x > TRANSITION_BORDER_WEST) \
+	&& (loc.x < TRANSITION_BORDER_EAST) \
+	&& (loc.y > TRANSITION_BORDER_SOUTH) \
+	&& (loc.y < TRANSITION_BORDER_NORTH)
+
diff --git a/code/game/gamemodes/blob/powers.dm b/code/game/gamemodes/blob/powers.dm
index c6d069e927a..82c4d85aeaf 100644
--- a/code/game/gamemodes/blob/powers.dm
+++ b/code/game/gamemodes/blob/powers.dm
@@ -328,6 +328,11 @@
 
 	if(!can_attack())
 		return
+
+	if(!is_location_within_transition_boundaries(T))
+		to_chat(src, "You can't expand here...")
+		return
+
 	var/obj/structure/blob/B = locate() in T
 	if(B)
 		to_chat(src, "There is a blob here!")
diff --git a/code/game/gamemodes/blob/theblob.dm b/code/game/gamemodes/blob/theblob.dm
index 5867a920a26..5c1762bfe99 100644
--- a/code/game/gamemodes/blob/theblob.dm
+++ b/code/game/gamemodes/blob/theblob.dm
@@ -93,6 +93,8 @@
 		var/dirn = pick(dirs)
 		dirs.Remove(dirn)
 		var/turf/T = get_step(src, dirn)
+		if(!is_location_within_transition_boundaries(T))
+			continue
 		var/obj/structure/blob/B = (locate(/obj/structure/blob) in T)
 		if(!B)
 			expand(T,1,a_color)//No blob here so try and expand
@@ -127,6 +129,8 @@
 			else	T = null
 
 	if(!T)	return 0
+	if(!is_location_within_transition_boundaries(T))
+		return
 	var/obj/structure/blob/normal/B = new /obj/structure/blob/normal(src.loc, min(obj_integrity, 30))
 	B.color = a_color
 	B.density = 1