diff --git a/code/datums/components/adjust_fishing_difficulty.dm b/code/datums/components/adjust_fishing_difficulty.dm
index 4e329b03940..d4b7b28492c 100644
--- a/code/datums/components/adjust_fishing_difficulty.dm
+++ b/code/datums/components/adjust_fishing_difficulty.dm
@@ -96,9 +96,9 @@
 		if(challenge)
 			UnregisterSignal(challenge, COMSIG_FISHING_CHALLENGE_GET_DIFFICULTY)
 	else
-		RegisterSignal(user, COMSIG_MOB_BEGIN_FISHING, PROC_REF(on_minigame_started))
+		RegisterSignal(user, COMSIG_MOB_BEGIN_FISHING, PROC_REF(on_minigame_started), TRUE)
 		if(challenge)
-			RegisterSignal(challenge, COMSIG_FISHING_CHALLENGE_GET_DIFFICULTY, PROC_REF(adjust_difficulty))
+			RegisterSignal(challenge, COMSIG_FISHING_CHALLENGE_GET_DIFFICULTY, PROC_REF(adjust_difficulty), TRUE)
 	challenge?.update_difficulty()
 
 /datum/component/adjust_fishing_difficulty/proc/on_minigame_started(mob/living/source, datum/fishing_challenge/challenge)
diff --git a/code/datums/mocking/client.dm b/code/datums/mocking/client.dm
index 4b724ef705e..8819cacb920 100644
--- a/code/datums/mocking/client.dm
+++ b/code/datums/mocking/client.dm
@@ -21,6 +21,10 @@
 	/// The key for this mock interface
 	var/key = "mockclient"
 
+	/// Mock ban cache to avoid runtimes when testing bans
+	var/ban_cache = null
+	var/ban_cache_start = 0
+
 	/// client prefs
 	var/fps
 	var/hotkeys
@@ -51,3 +55,6 @@
 
 /datum/client_interface/proc/update_ambience_pref()
 	return
+
+/datum/client_interface/proc/get_award_status(achievement_type, mob/user, value = 1)
+	return FALSE
diff --git a/code/datums/quirks/negative_quirks/addict.dm b/code/datums/quirks/negative_quirks/addict.dm
index 8574c6060d6..09b25ef46b2 100644
--- a/code/datums/quirks/negative_quirks/addict.dm
+++ b/code/datums/quirks/negative_quirks/addict.dm
@@ -102,7 +102,7 @@
 	return ..()
 
 /datum/quirk/item_quirk/addict/remove()
-	if(quirk_holder && reagent_instance)
+	if(!QDELETED(quirk_holder) && reagent_instance)
 		for(var/addiction_type in subtypesof(/datum/addiction))
 			quirk_holder.mind.remove_addiction_points(addiction_type, MAX_ADDICTION_POINTS)
 
diff --git a/code/datums/quirks/neutral_quirks/borg_ready.dm b/code/datums/quirks/neutral_quirks/borg_ready.dm
index 371e02a03c5..f623dd47de0 100644
--- a/code/datums/quirks/neutral_quirks/borg_ready.dm
+++ b/code/datums/quirks/neutral_quirks/borg_ready.dm
@@ -8,7 +8,7 @@
 	medical_record_text = "Patient is a registered brain donor for Robotics research."
 
 /datum/quirk/item_quirk/borg_ready/add_unique(client/client_source)
-	if(is_banned_from(quirk_holder.ckey, JOB_CYBORG))
+	if(is_banned_from(client_source.ckey, JOB_CYBORG))
 		return FALSE
 	var/obj/item/clothing/accessory/dogtag/borg_ready/borgtag = new(get_turf(quirk_holder))
 	give_item_to_holder(borgtag, list(LOCATION_BACKPACK = ITEM_SLOT_BACKPACK, LOCATION_HANDS = ITEM_SLOT_HANDS))
diff --git a/code/datums/quirks/neutral_quirks/foreigner.dm b/code/datums/quirks/neutral_quirks/foreigner.dm
index da317a7e66a..7cdb85cace5 100644
--- a/code/datums/quirks/neutral_quirks/foreigner.dm
+++ b/code/datums/quirks/neutral_quirks/foreigner.dm
@@ -15,6 +15,8 @@
 		human_holder.grant_language(/datum/language/uncommon, source = LANGUAGE_QUIRK)
 
 /datum/quirk/foreigner/remove()
+	if(QDELETED(quirk_holder))
+		return
 	var/mob/living/carbon/human/human_holder = quirk_holder
 	human_holder.remove_blocked_language(/datum/language/common)
 	if(ishumanbasic(human_holder))
diff --git a/code/modules/unit_tests/quirks.dm b/code/modules/unit_tests/quirks.dm
index cca2c312cfe..69630f66291 100644
--- a/code/modules/unit_tests/quirks.dm
+++ b/code/modules/unit_tests/quirks.dm
@@ -75,3 +75,36 @@
 		if(!isnull(species_to_test[last_species]))
 			TEST_ASSERT(!(species_to_test[last_species] in quirk.mail_goodies), \
 				"Blood deficiency quirk did not update correctly for [species_type]! ([last_species] did not get its blood bag removed)")
+
+/// Ensures that all quirks correctly initialized when added
+/datum/unit_test/quirk_validity
+
+/datum/unit_test/quirk_validity/Run()
+	// Required for language quirks to function properly
+	// Assigning this manually as config is empty
+	GLOB.uncommon_roundstart_languages = list(/datum/language/uncommon)
+
+	for (var/datum/quirk/quirk_type as anything in subtypesof(/datum/quirk))
+		if (initial(quirk_type.abstract_parent_type) == quirk_type)
+			continue
+
+		var/mob/dead/new_player/abstract_player = allocate(/mob/dead/new_player)
+		var/datum/client_interface/roundstart_mock_client = new()
+		abstract_player.mock_client = roundstart_mock_client
+		roundstart_mock_client.prefs = new(roundstart_mock_client)
+		var/mob/living/carbon/human/new_character = allocate(/mob/living/carbon/human/consistent)
+		new_character.mind_initialize()
+		abstract_player.new_character = new_character
+		if (!new_character.add_quirk(quirk_type, roundstart_mock_client))
+			TEST_FAIL("Failed to initialize quirk [quirk_type] on a roundstart character!")
+
+		var/mob/living/carbon/human/latejoin_character = allocate(/mob/living/carbon/human/consistent)
+		var/datum/client_interface/latejoin_mock_client = new()
+		latejoin_mock_client.prefs = new(latejoin_mock_client)
+		latejoin_character.mock_client = latejoin_mock_client
+		latejoin_character.mind_initialize()
+		if (!latejoin_character.add_quirk(quirk_type, latejoin_mock_client))
+			TEST_FAIL("Failed to initialize quirk [quirk_type] on a latejoin character!")
+
+	// Clean up after ourselves
+	GLOB.uncommon_roundstart_languages.Cut()