diff --git a/code/modules/client/client_procs.dm b/code/modules/client/client_procs.dm
index e88beecfe0..6a7c12a10c 100644
--- a/code/modules/client/client_procs.dm
+++ b/code/modules/client/client_procs.dm
@@ -3,6 +3,8 @@
 	////////////
 #define UPLOAD_LIMIT		1048576	//Restricts client uploads to the server to 1MB //Could probably do with being lower.
 
+GLOBAL_LIST_INIT(blacklisted_builds, list(1407 = "bug preventing client display overrides from working leads to clients being able to see things/mobs they shouldn't be able to see"))
+
 #define LIMITER_SIZE	5
 #define CURRENT_SECOND	1
 #define SECOND_COUNT	2
@@ -228,7 +230,18 @@ GLOBAL_LIST_EMPTY(external_rsc_urls)
 
 
 	. = ..()	//calls mob.Login()
-
+	#if DM_VERSION >= 512
+	if (byond_build in GLOB.blacklisted_builds)
+		log_access("Failed login: blacklisted byond version")
+		to_chat(src, "<span class='userdanger'>Your version of byond is blacklisted.</span>")
+		to_chat(src, "<span class='danger'>Byond build [byond_build] ([byond_version].[byond_build]) has been blacklisted for the following reason: [GLOB.blacklisted_builds[byond_build]].</span>")
+		to_chat(src, "<span class='danger'>Please download a new version of byond. if [byond_build] is the latest, you can go to http://www.byond.com/download/build/ to download other versions.</span>")
+		if(connecting_admin)
+			to_chat(src, "As an admin, you are being allowed to continue using this version, but please consider changing byond versions")
+		else 
+			qdel(src)
+			return
+	#endif
 	if(SSinput.initialized)
 		set_macros()