diff --git a/code/__DEFINES/mobs.dm b/code/__DEFINES/mobs.dm
index 7c082f0b228..66715dbf879 100644
--- a/code/__DEFINES/mobs.dm
+++ b/code/__DEFINES/mobs.dm
@@ -836,6 +836,9 @@ GLOBAL_LIST_INIT(layers_to_offset, list(
 /// The layer above mutant body parts
 #define ABOVE_BODY_FRONT_LAYER (BODY_FRONT_LAYER-1)
 
+/// We need gloves to layer on top of modsuit chestplates because we need the hole in the suit filled in if the user lacks a limb
+#define MOD_CHESTPLATE_LAYER (GLOVES_LAYER+0.5)
+
 /// If gravity must be present to perform action (can't use pens without gravity)
 #define NEED_GRAVITY (1<<0)
 /// If reading is required to perform action (can't read a book if you are illiterate)
diff --git a/code/modules/mod/mod_activation.dm b/code/modules/mod/mod_activation.dm
index 7da28c17a3a..a9a793d8a2f 100644
--- a/code/modules/mod/mod_activation.dm
+++ b/code/modules/mod/mod_activation.dm
@@ -20,13 +20,15 @@
 	var/obj/item/part = locate(part_reference) in get_parts()
 	if(!istype(part) || user.incapacitated)
 		return
-	if(active || activating)
-		balloon_alert(user, "deactivate the suit first!")
+	if(activating)
+		balloon_alert(user, "currently [active ? "unsealing" : "sealing"]!")
 		playsound(src, 'sound/machines/scanner/scanbuzz.ogg', 25, TRUE, SILENCED_SOUND_EXTRARANGE)
 		return
 	var/parts_to_check = parts - part
 	if(part.loc == src)
 		deploy(user, part)
+		if(active && !delayed_seal_part(part))
+			return
 		SEND_SIGNAL(src, COMSIG_MOD_DEPLOYED, user)
 		for(var/obj/item/checking_part as anything in parts_to_check)
 			if(checking_part.loc != src)
@@ -34,6 +36,8 @@
 			choose_deploy(user)
 			break
 	else
+		if(active && !delayed_seal_part(part))
+			return
 		retract(user, part)
 		SEND_SIGNAL(src, COMSIG_MOD_RETRACTED, user)
 		for(var/obj/item/checking_part as anything in parts_to_check)
@@ -44,8 +48,8 @@
 
 /// Quickly deploys all parts (or retracts if all are on the wearer)
 /obj/item/mod/control/proc/quick_deploy(mob/user)
-	if(active || activating)
-		balloon_alert(user, "deactivate the suit first!")
+	if(activating)
+		balloon_alert(user, "currently sealing/unsealing!")
 		playsound(src, 'sound/machines/scanner/scanbuzz.ogg', 25, TRUE, SILENCED_SOUND_EXTRARANGE)
 		return FALSE
 	var/deploy = TRUE
@@ -57,7 +61,11 @@
 	for(var/obj/item/part as anything in get_parts())
 		if(deploy && part.loc == src)
 			deploy(null, part)
+			if(active && !delayed_seal_part(part))
+				return
 		else if(!deploy && part.loc != src)
+			if(active && !delayed_seal_part(part))
+				return
 			retract(null, part)
 	wearer.visible_message(span_notice("[wearer]'s [src] [deploy ? "deploys" : "retracts"] its parts with a mechanical hiss."),
 		span_notice("[src] [deploy ? "deploys" : "retracts"] its parts with a mechanical hiss."),
@@ -137,11 +145,6 @@
 	if(!force_deactivate && (SEND_SIGNAL(src, COMSIG_MOD_ACTIVATE, user) & MOD_CANCEL_ACTIVATE))
 		playsound(src, 'sound/machines/scanner/scanbuzz.ogg', 25, TRUE, SILENCED_SOUND_EXTRARANGE)
 		return FALSE
-	for(var/obj/item/part as anything in get_parts())
-		if(!force_deactivate && part.loc == src)
-			balloon_alert(user, "deploy all parts first!")
-			playsound(src, 'sound/machines/scanner/scanbuzz.ogg', 25, TRUE, SILENCED_SOUND_EXTRARANGE)
-			return FALSE
 	if(locked && !active && !allowed(user) && !force_deactivate)
 		balloon_alert(user, "access insufficient!")
 		playsound(src, 'sound/machines/scanner/scanbuzz.ogg', 25, TRUE, SILENCED_SOUND_EXTRARANGE)
@@ -166,29 +169,45 @@
 	activating = TRUE
 	mod_link.end_call()
 	to_chat(wearer, span_notice("MODsuit [active ? "shutting down" : "starting up"]."))
-	for(var/obj/item/part as anything in get_parts())
-		var/datum/mod_part/part_datum = get_part_datum(part)
-		if(do_after(wearer, activation_step_time, wearer, MOD_ACTIVATION_STEP_FLAGS, extra_checks = CALLBACK(src, PROC_REF(get_wearer)), hidden = TRUE))
-			to_chat(wearer, span_notice("[part] [active ? part_datum.unsealed_message : part_datum.sealed_message]."))
-			playsound(src, 'sound/vehicles/mecha/mechmove03.ogg', 25, TRUE, SHORT_RANGE_SOUND_EXTRARANGE)
-			seal_part(part, is_sealed = !active)
+	//deploy the control unit
 	if(do_after(wearer, activation_step_time, wearer, MOD_ACTIVATION_STEP_FLAGS, extra_checks = CALLBACK(src, PROC_REF(get_wearer)), hidden = TRUE))
-		to_chat(wearer, span_notice("Systems [active ? "shut down. Parts unsealed. Goodbye" : "started up. Parts sealed. Welcome"], [wearer]."))
-		if(ai_assistant)
-			to_chat(ai_assistant, span_notice("<b>SYSTEMS [active ? "DEACTIVATED. GOODBYE" : "ACTIVATED. WELCOME"]: \"[ai_assistant]\"</b>"))
-		finish_activation(is_on = !active)
-		if(active)
-			playsound(src, 'sound/machines/synth/synth_yes.ogg', 50, TRUE, SHORT_RANGE_SOUND_EXTRARANGE, frequency = 6000)
-			if(!malfunctioning)
-				wearer.playsound_local(get_turf(src), 'sound/vehicles/mecha/nominal.ogg', 50)
-		else
-			playsound(src, 'sound/machines/synth/synth_no.ogg', 50, TRUE, SHORT_RANGE_SOUND_EXTRARANGE, frequency = 6000)
+		playsound(src, active ? 'sound/machines/synth/synth_no.ogg' : 'sound/machines/synth/synth_yes.ogg', 50, TRUE, SHORT_RANGE_SOUND_EXTRARANGE, frequency = 8000)
+	else
+		activating = FALSE
+		return
+
+	for(var/obj/item/part as anything in get_parts()) //seals/unseals all deployed parts
+		if(part.loc == src)
+			continue
+		delayed_seal_part(part, no_activation = TRUE)
+
+	//finish activation
+	to_chat(wearer, span_notice("Systems [active ? "shut down. Parts unsealed. Goodbye" : "started up. Parts sealed. Welcome"], [wearer]."))
+	if(ai_assistant)
+		to_chat(ai_assistant, span_notice("<b>SYSTEMS [active ? "DEACTIVATED. GOODBYE" : "ACTIVATED. WELCOME"]: \"[ai_assistant]\"</b>"))
+	finish_activation(is_on = !active)
+	if(active)
+		playsound(src, 'sound/machines/synth/synth_yes.ogg', 50, TRUE, SHORT_RANGE_SOUND_EXTRARANGE, frequency = 6000)
+		if(!malfunctioning)
+			wearer.playsound_local(get_turf(src), 'sound/vehicles/mecha/nominal.ogg', 50)
+	else
+		playsound(src, 'sound/machines/synth/synth_no.ogg', 50, TRUE, SHORT_RANGE_SOUND_EXTRARANGE, frequency = 6000)
+
 	activating = FALSE
 	SEND_SIGNAL(src, COMSIG_MOD_TOGGLED, user)
 	return TRUE
 
+/obj/item/mod/control/proc/delayed_seal_part(obj/item/clothing/part, no_activation = FALSE)
+	. = FALSE
+	var/datum/mod_part/part_datum = get_part_datum(part)
+	if(do_after(wearer, activation_step_time, wearer, MOD_ACTIVATION_STEP_FLAGS, extra_checks = CALLBACK(src, PROC_REF(get_wearer)), hidden = TRUE))
+		to_chat(wearer, span_notice("[part] [!part_datum.sealed ? part_datum.sealed_message : part_datum.unsealed_message]."))
+		playsound(src, 'sound/vehicles/mecha/mechmove03.ogg', 25, TRUE, SHORT_RANGE_SOUND_EXTRARANGE)
+		seal_part(part, is_sealed = !part_datum.sealed, no_activation = no_activation)
+		return TRUE
+
 ///Seals or unseals the given part.
-/obj/item/mod/control/proc/seal_part(obj/item/clothing/part, is_sealed)
+/obj/item/mod/control/proc/seal_part(obj/item/clothing/part, is_sealed, no_activation = FALSE)
 	var/datum/mod_part/part_datum = get_part_datum(part)
 	part_datum.sealed = is_sealed
 	if(part_datum.sealed)
@@ -211,6 +230,22 @@
 	wearer.update_obscured_slots(part.visor_flags_inv)
 	if((part.clothing_flags & (MASKINTERNALS|HEADINTERNALS)) && wearer.invalid_internals())
 		wearer.cutoff_internals()
+	if(!active || no_activation)
+		return
+	// these only matter during sealing and unsealing while active via deployment
+	if(is_sealed)
+		for(var/obj/item/mod/module/module as anything in modules)
+			if(!module.has_required_parts(list("[part.slot_flags]" = part_datum), need_extended = TRUE))
+				continue
+			module.on_suit_activation()
+	else
+		for(var/obj/item/mod/module/module as anything in modules)
+			if(!module.has_required_parts(list("[part.slot_flags]" = part_datum), need_extended = TRUE))
+				continue
+			module.on_suit_deactivation()
+			if(!module.active || (module.allow_flags & MODULE_ALLOW_INACTIVE))
+				continue
+			module.deactivate(display_message = FALSE)
 
 /// Finishes the suit's activation
 /obj/item/mod/control/proc/finish_activation(is_on)
@@ -219,9 +254,13 @@
 	active = is_on
 	if(active)
 		for(var/obj/item/mod/module/module as anything in modules)
+			if(!module.has_required_parts(mod_parts, need_extended = TRUE))
+				continue
 			module.on_suit_activation()
 	else
 		for(var/obj/item/mod/module/module as anything in modules)
+			if(!module.has_required_parts(mod_parts, need_extended = TRUE)) //it probably will runtime if we dont do this
+				continue
 			module.on_suit_deactivation()
 	update_speed()
 	update_appearance(UPDATE_ICON_STATE)
diff --git a/code/modules/mod/mod_control.dm b/code/modules/mod/mod_control.dm
index df2096ae367..21bf8509d6b 100644
--- a/code/modules/mod/mod_control.dm
+++ b/code/modules/mod/mod_control.dm
@@ -219,6 +219,10 @@
 /obj/item/mod/control/allow_attack_hand_drop(mob/user)
 	if(user != wearer)
 		return ..()
+	if(active)
+		balloon_alert(wearer, "deactivate the suit first!")
+		playsound(src, 'sound/machines/scanner/scanbuzz.ogg', 25, FALSE, SILENCED_SOUND_EXTRARANGE)
+		return
 	for(var/obj/item/part as anything in get_parts())
 		if(part.loc != src)
 			balloon_alert(user, "retract parts first!")
@@ -228,6 +232,10 @@
 /obj/item/mod/control/mouse_drop_dragged(atom/over_object, mob/user)
 	if(user != wearer || !istype(over_object, /atom/movable/screen/inventory/hand))
 		return
+	if(active)
+		balloon_alert(wearer, "deactivate the suit first!")
+		playsound(src, 'sound/machines/scanner/scanbuzz.ogg', 25, FALSE, SILENCED_SOUND_EXTRARANGE)
+		return
 	for(var/obj/item/part as anything in get_parts())
 		if(part.loc != src)
 			balloon_alert(wearer, "retract parts first!")
@@ -575,7 +583,7 @@
 	new_module.on_install()
 	if(wearer)
 		new_module.on_equip()
-	if(active)
+	if(active && new_module.has_required_parts(mod_parts, need_extended = TRUE))
 		new_module.on_suit_activation()
 	if(user)
 		balloon_alert(user, "[new_module] added")
@@ -679,8 +687,6 @@
 			part.forceMove(src)
 			return
 		retract(wearer, part)
-		if(active)
-			INVOKE_ASYNC(src, PROC_REF(toggle_activate), wearer, TRUE)
 
 /obj/item/mod/control/proc/on_part_destruction(obj/item/part, damage_flag)
 	SIGNAL_HANDLER
diff --git a/code/modules/mod/mod_theme.dm b/code/modules/mod/mod_theme.dm
index 76f9063df0b..664f9118b83 100644
--- a/code/modules/mod/mod_theme.dm
+++ b/code/modules/mod/mod_theme.dm
@@ -62,6 +62,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -203,6 +205,8 @@
 				SEALED_COVER = HEADCOVERSEYES,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
 				UNSEALED_MESSAGE = CHESTPLATE_UNSEAL_MESSAGE,
@@ -266,6 +270,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -334,6 +340,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -406,6 +414,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -480,6 +490,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = THICKMATERIAL|STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT|HIDEBELT,
@@ -512,6 +524,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = THICKMATERIAL|STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT|HIDEBELT,
@@ -588,6 +602,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				UNSEALED_MESSAGE = CHESTPLATE_UNSEAL_MESSAGE,
 				SEALED_MESSAGE = CHESTPLATE_SEAL_MESSAGE,
@@ -660,6 +676,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -693,6 +711,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -773,6 +793,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -845,6 +867,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -912,6 +936,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -979,6 +1005,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -1052,6 +1080,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -1120,6 +1150,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -1195,6 +1227,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -1228,6 +1262,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -1301,6 +1337,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -1376,6 +1414,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT|HIDEMUTWINGS,
 				CAN_OVERSLOT = TRUE,
@@ -1461,6 +1501,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -1531,6 +1573,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL|CASTING_CLOTHES,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -1600,6 +1644,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -1671,6 +1717,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -1739,6 +1787,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -1806,6 +1856,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -1837,6 +1889,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -1919,6 +1973,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -1988,6 +2044,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -2052,6 +2110,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -2118,6 +2178,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL,
 				SEALED_CLOTHING = STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
@@ -2183,6 +2245,8 @@
 				SEALED_MESSAGE = HELMET_SEAL_MESSAGE,
 			),
 			/obj/item/clothing/suit/mod = list(
+				UNSEALED_LAYER = MOD_CHESTPLATE_LAYER,
+				SEALED_LAYER = MOD_CHESTPLATE_LAYER,
 				UNSEALED_CLOTHING = THICKMATERIAL|STOPSPRESSUREDAMAGE,
 				SEALED_INVISIBILITY = HIDEJUMPSUIT,
 				UNSEALED_MESSAGE = CHESTPLATE_UNSEAL_MESSAGE,
diff --git a/code/modules/mod/modules/_module.dm b/code/modules/mod/modules/_module.dm
index 6065a486d0c..3055d0616f9 100644
--- a/code/modules/mod/modules/_module.dm
+++ b/code/modules/mod/modules/_module.dm
@@ -108,6 +108,16 @@
 		if(mod.wearer)
 			balloon_alert(mod.wearer, "not active!")
 		return
+	if(!has_required_parts(mod.mod_parts, need_extended = TRUE))
+		if(mod.wearer)
+			balloon_alert(mod.wearer, "required parts inactive!")
+			var/list/slot_strings = list()
+			for(var/slot in required_slots)
+				var/list/slot_list = parse_slot_flags(slot)
+				slot_strings += (length(slot_list) == 1 ? "" : "one of ") + english_list(slot_list, and_text = " or ")
+			to_chat(mod.wearer, span_warning("[src] requires these slots to be deployed: [english_list(slot_strings)]"))
+			playsound(src, 'sound/machines/scanner/scanbuzz.ogg', 25, TRUE, SILENCED_SOUND_EXTRARANGE)
+		return
 	if(module_type != MODULE_USABLE)
 		if(active)
 			deactivate()
diff --git a/icons/mob/clothing/modsuit/mod_clothing.dmi b/icons/mob/clothing/modsuit/mod_clothing.dmi
index aa9b6feca11..071db6ba93c 100644
Binary files a/icons/mob/clothing/modsuit/mod_clothing.dmi and b/icons/mob/clothing/modsuit/mod_clothing.dmi differ