diff --git a/code/__DEFINES/mode.dm b/code/__DEFINES/mode.dm
index e46f344220..ea3aef5fa4 100644
--- a/code/__DEFINES/mode.dm
+++ b/code/__DEFINES/mode.dm
@@ -58,6 +58,7 @@
 #define MODE_RANDOM_HIVE (1<<12)// Makes Join-as-Xeno choose a hive to join as burrowed larva at random rather than at user's input..
 #define MODE_THUNDERSTORM (1<<13)// Enables thunderstorm effects on maps that are compatible with it. (Lit exterior tiles, rain effects)
 #define MODE_FACTION_CLASH (1<<14)// Disables scopes, sniper sentries, OBs, shooting corpses, dragging enemy corpses, stripping enemy corpses
+#define MODE_NO_XENO_EVOLVE (1<<15) // Stops all xenos from evolving
 
 // Gamemode Toggleable Flags
 #define MODE_NO_SNIPER_SENTRY (1<<0) /// Upgrade kits will no longer allow you to select long-range upgrades
diff --git a/code/game/gamemodes/colonialmarines/ai/colonialmarines_ai.dm b/code/game/gamemodes/colonialmarines/ai/colonialmarines_ai.dm
index 3ed373c4ad..8d41f5282b 100644
--- a/code/game/gamemodes/colonialmarines/ai/colonialmarines_ai.dm
+++ b/code/game/gamemodes/colonialmarines/ai/colonialmarines_ai.dm
@@ -26,6 +26,7 @@
 
 	static_comms_amount = 0
 	requires_comms = FALSE
+	flags_round_type = MODE_NO_XENO_EVOLVE
 	toggleable_flags = MODE_NO_JOIN_AS_XENO|MODE_HARDCORE_PERMA
 
 /datum/game_mode/colonialmarines/ai/can_start()
diff --git a/code/modules/mob/living/carbon/xenomorph/Evolution.dm b/code/modules/mob/living/carbon/xenomorph/Evolution.dm
index 332f8d1778..bf46934730 100644
--- a/code/modules/mob/living/carbon/xenomorph/Evolution.dm
+++ b/code/modules/mob/living/carbon/xenomorph/Evolution.dm
@@ -202,6 +202,10 @@
 		to_chat(src, SPAN_WARNING("Nuh-uh."))
 		return FALSE
 
+	if(SSticker?.mode?.flags_round_type & MODE_NO_XENO_EVOLVE)
+		to_chat(src, SPAN_WARNING("This mode disallows xeno evolution."))
+		return FALSE
+
 	if(lock_evolve)
 		to_chat(src, SPAN_WARNING("You are banished and cannot reach the hivemind."))
 		return FALSE