diff --git a/code/controllers/subsystem/mapping.dm b/code/controllers/subsystem/mapping.dm
index 76910e342dc..fe8d6e19bee 100644
--- a/code/controllers/subsystem/mapping.dm
+++ b/code/controllers/subsystem/mapping.dm
@@ -49,6 +49,8 @@ SUBSYSTEM_DEF(mapping)
 	var/datum/space_level/transit
 	var/datum/space_level/empty_space
 	var/num_of_res_levels = 1
+	/// True when in the process of adding a new Z-level, global locking
+	var/adding_new_zlevel = FALSE
 
 /datum/controller/subsystem/mapping/New()
 	..()
diff --git a/code/modules/mapping/space_management/zlevel_manager.dm b/code/modules/mapping/space_management/zlevel_manager.dm
index 6129c5fd2b6..35235579a44 100644
--- a/code/modules/mapping/space_management/zlevel_manager.dm
+++ b/code/modules/mapping/space_management/zlevel_manager.dm
@@ -17,6 +17,8 @@
 		z_list += S
 
 /datum/controller/subsystem/mapping/proc/add_new_zlevel(name, traits = list(), z_type = /datum/space_level)
+	UNTIL(!adding_new_zlevel)
+	adding_new_zlevel = TRUE
 	SEND_GLOBAL_SIGNAL(COMSIG_GLOB_NEW_Z, args)
 	var/new_z = z_list.len + 1
 	if (world.maxz < new_z)
@@ -25,6 +27,7 @@
 	// TODO: sleep here if the Z level needs to be cleared
 	var/datum/space_level/S = new z_type(new_z, name, traits)
 	z_list += S
+	adding_new_zlevel = FALSE
 	return S
 
 /datum/controller/subsystem/mapping/proc/get_level(z)