diff --git a/code/modules/games/cards.dm b/code/modules/games/cards.dm
index ad5e29ab160..83d32b64ac4 100644
--- a/code/modules/games/cards.dm
+++ b/code/modules/games/cards.dm
@@ -50,10 +50,16 @@
 
 /obj/item/deck/Initialize(mapload)
 	. = ..()
+	build_decks()
+	update_icon(UPDATE_ICON_STATE)
+
+/obj/item/deck/proc/build_decks()
+	if(length(cards))
+		// prevent building decks more than once
+		return
 	for(var/deck in 1 to deck_size)
 		build_deck()
 	deck_total = length(cards)
-	update_icon(UPDATE_ICON_STATE)
 
 /obj/item/deck/proc/build_deck()
 	return
@@ -227,8 +233,10 @@
 	var/mob/living/user = usr
 	if(cooldown < world.time - 1 SECONDS)
 		cards = shuffle(cards)
-		user.visible_message("<span class='notice'>[user] shuffles [src].</span>")
-		playsound(user, 'sound/items/cardshuffle.ogg', 50, 1)
+
+		if(user)
+			user.visible_message("<span class='notice'>[user] shuffles [src].</span>")
+			playsound(user, 'sound/items/cardshuffle.ogg', 50, TRUE)
 		cooldown = world.time
 
 
diff --git a/code/modules/unit_tests/_unit_tests.dm b/code/modules/unit_tests/_unit_tests.dm
index 7f234307d41..76f2504ef03 100644
--- a/code/modules/unit_tests/_unit_tests.dm
+++ b/code/modules/unit_tests/_unit_tests.dm
@@ -2,6 +2,7 @@
 //Keep this sorted alphabetically
 
 #ifdef UNIT_TESTS
+#include "games\test_cards.dm"
 #include "jobs\test_job_globals.dm"
 #include "aicard_icons.dm"
 #include "announcements.dm"
diff --git a/code/modules/unit_tests/games/test_cards.dm b/code/modules/unit_tests/games/test_cards.dm
new file mode 100644
index 00000000000..bde0b9f1f8b
--- /dev/null
+++ b/code/modules/unit_tests/games/test_cards.dm
@@ -0,0 +1,30 @@
+/datum/unit_test/card_deck/proc/validate_deck(obj/item/deck/deck)
+	var/list/card_count = list()
+	for(var/datum/playingcard/card in deck.cards)
+		if(card_count[card.name] == null)
+			card_count[card.name] = 1
+		else if(card.name == "Joker")
+			card_count[card.name]++
+		else
+			// duplicate card in deck
+			return FALSE
+
+	if(length(card_count) != 53) // 2 Jokers, so 53 unique cards
+		return FALSE
+	return TRUE
+
+
+/datum/unit_test/card_deck/Run()
+	// setup
+	var/loc = pick(block(run_loc_bottom_left, run_loc_top_right))
+	var/obj/item/deck/cards/cards = new /obj/item/deck/cards(loc)
+	cards.build_decks()
+
+	// is deck proper upon spawning
+	if(!validate_deck(cards))
+		Fail("52 card deck not initialized correctly.")
+
+	// is deck proper after shuffling
+	cards.deckshuffle()
+	if(!validate_deck(cards))
+		Fail("52 card deck broken after shuffling.")