diff --git a/.github/alternate_byond_versions.txt b/.github/alternate_byond_versions.txt
index c96908590dac..7b50af46885e 100644
--- a/.github/alternate_byond_versions.txt
+++ b/.github/alternate_byond_versions.txt
@@ -5,5 +5,3 @@
 # Format is version: map
 # Example:
 # 500.1337: runtimestation
-
-515.1630: lv624
diff --git a/.tgs.yml b/.tgs.yml
index ba3fc6b26c66..ed84385e3c36 100644
--- a/.tgs.yml
+++ b/.tgs.yml
@@ -1,5 +1,5 @@
 version: 1
-byond: "514.1588"
+byond: "515.1627"
 static_files:
   - name: config
   - name: data
diff --git a/code/__DEFINES/__spacemandmm.dm b/code/__DEFINES/__spacemandmm.dm
index b62bbee4259a..9a044949db3e 100644
--- a/code/__DEFINES/__spacemandmm.dm
+++ b/code/__DEFINES/__spacemandmm.dm
@@ -40,5 +40,5 @@
 /world/Del()
 	var/debug_server = world.GetConfig("env", "AUXTOOLS_DEBUG_DLL")
 	if (debug_server)
-		LIBCALL(debug_server, "auxtools_shutdown")()
+		call_ext(debug_server, "auxtools_shutdown")()
 	. = ..()
diff --git a/code/__DEFINES/_macros.dm b/code/__DEFINES/_macros.dm
index 31f4b2aca084..07c3eb664e61 100644
--- a/code/__DEFINES/_macros.dm
+++ b/code/__DEFINES/_macros.dm
@@ -8,17 +8,8 @@
 
 #define subtypesof(A) (typesof(A) - A)
 
-#ifdef EXPERIMENT_515_DONT_CACHE_REF
 /// Takes a datum as input, returns its ref string
 #define text_ref(datum) ref(datum)
-#else
-/// Takes a datum as input, returns its ref string, or a cached version of it
-/// This allows us to cache \ref creation, which ensures it'll only ever happen once per datum, saving string tree time
-/// It is slightly less optimal then a []'d datum, but the cost is massively outweighed by the potential savings
-/// It will only work for datums mind, for datum reasons
-/// : because of the embedded typecheck
-#define text_ref(datum) (isdatum(datum) ? (datum:cached_ref ||= "\ref[datum]") : ("\ref[datum]"))
-#endif
 
 #define addToListNoDupe(L, index) if(L) L[index] = null; else L = list(index)
 
diff --git a/code/__HELPERS/nameof.dm b/code/__HELPERS/nameof.dm
index 7cd5777f4652..5a2fd60e7100 100644
--- a/code/__HELPERS/nameof.dm
+++ b/code/__HELPERS/nameof.dm
@@ -8,8 +8,4 @@
 /**
  * NAMEOF that actually works in static definitions because src::type requires src to be defined
  */
-#if DM_VERSION >= 515
 #define NAMEOF_STATIC(datum, X) (nameof(type::##X))
-#else
-#define NAMEOF_STATIC(datum, X) (#X || ##datum.##X)
-#endif
diff --git a/code/_byond_version_compat.dm b/code/_byond_version_compat.dm
index 26968f0f837c..c41fdc830e6e 100644
--- a/code/_byond_version_compat.dm
+++ b/code/_byond_version_compat.dm
@@ -1,56 +1,17 @@
 // This file contains defines allowing targeting byond versions newer than the supported
 
 //Update this whenever you need to take advantage of more recent byond features
-#define MIN_COMPILER_VERSION 514
-#define MIN_COMPILER_BUILD 1588
+#define MIN_COMPILER_VERSION 515
+#define MIN_COMPILER_BUILD 1627
 #if (DM_VERSION < MIN_COMPILER_VERSION || DM_BUILD < MIN_COMPILER_BUILD) && !defined(SPACEMAN_DMM) && !defined(OPENDREAM)
 //Don't forget to update this part
-#error Your version of BYOND is too out-of-date to compile this project. Go to https://secure.byond.com/download and update.
-#error You need version 514.1588 or higher
-#endif
-
-/*
-#if (DM_VERSION == 514 && DM_BUILD > 1575 && DM_BUILD <= 1577)
-#error Your version of BYOND currently has a crashing issue that will prevent you from running Dream Daemon test servers.
-#error We require developers to test their content, so an inability to test means we cannot allow the compile.
-#error Please consider downgrading to 514.1575 or lower.
-#endif
-*/
-
-/*
-// Keep savefile compatibilty at minimum supported level
-#if DM_VERSION >= 515
-/savefile/byond_version = MIN_COMPILER_VERSION
-#endif
-*/
-
-// 515 split call for external libraries into call_ext
-#if DM_VERSION < 515
-#define LIBCALL call
-#else
-#define LIBCALL call_ext
+#error Your version of BYOND is too out-of-date to compile this project. Go to https://www.byond.com/download and update.
+#error You need version 515.1627 or higher
 #endif
 
 // So we want to have compile time guarantees these methods exist on local type, unfortunately 515 killed the .proc/procname and .verb/verbname syntax so we have to use nameof()
 // For the record: GLOBAL_VERB_REF would be useless as verbs can't be global.
 
-#if DM_VERSION < 515
-
-/// Call by name proc references, checks if the proc exists on either this type or as a global proc.
-#define PROC_REF(X) (.proc/##X)
-/// Call by name verb references, checks if the verb exists on either this type or as a global verb.
-#define VERB_REF(X) (.verb/##X)
-
-/// Call by name proc reference, checks if the proc exists on either the given type or as a global proc
-#define TYPE_PROC_REF(TYPE, X) (##TYPE.proc/##X)
-/// Call by name verb reference, checks if the verb exists on either the given type or as a global verb
-#define TYPE_VERB_REF(TYPE, X) (##TYPE.verb/##X)
-
-/// Call by name proc reference, checks if the proc is an existing global proc
-#define GLOBAL_PROC_REF(X) (/proc/##X)
-
-#else
-
 /// Call by name proc references, checks if the proc exists on either this type or as a global proc.
 #define PROC_REF(X) (nameof(.proc/##X))
 /// Call by name verb references, checks if the verb exists on either this type or as a global verb.
@@ -64,16 +25,4 @@
 /// Call by name proc reference, checks if the proc is an existing global proc
 #define GLOBAL_PROC_REF(X) (/proc/##X)
 
-#endif
-
-#if (DM_VERSION == 515)
-/// fcopy will crash on 515 linux if given a non-existant file, instead of returning 0 like on 514 linux or 515 windows
-/// var case matches documentation for fcopy.
-/world/proc/__fcopy(Src, Dst)
-	if (istext(Src) && !fexists(Src))
-		return 0
-	return fcopy(Src, Dst)
 
-#define fcopy(Src, Dst) world.__fcopy(Src, Dst)
-
-#endif
diff --git a/code/_experiments.dm b/code/_experiments.dm
index 6e5addb5f992..39c4c45e7eda 100644
--- a/code/_experiments.dm
+++ b/code/_experiments.dm
@@ -3,29 +3,7 @@
 // Any flag you see here can be flipped with the `-D` CLI argument.
 // For example, if you want to enable EXPERIMENT_MY_COOL_FEATURE, compile with -DEXPERIMENT_MY_COOL_FEATURE
 
-// EXPERIMENT_515_QDEL_HARD_REFERENCE
-// - Hold a hard reference for qdeleted items, and check ref_count, rather than using refs. Requires 515+.
-
-// EXPERIMENT_515_DONT_CACHE_REF
-// - Avoids `text_ref` caching, aided by improvements to ref() speed in 515.
-
-#if DM_VERSION < 515
-
-// You can't X-macro custom names :(
-#ifdef EXPERIMENT_515_QDEL_HARD_REFERENCE
-#warn EXPERIMENT_515_QDEL_HARD_REFERENCE is only available on 515+
-#undef EXPERIMENT_515_QDEL_HARD_REFERENCE
-#endif
-
-#ifdef EXPERIMENT_515_DONT_CACHE_REF
-#warn EXPERIMENT_515_DONT_CACHE_REF is only available on 515+
-#undef EXPERIMENT_515_DONT_CACHE_REF
-#endif
-
-#elif defined(UNIT_TESTS)
-
-//#define EXPERIMENT_515_QDEL_HARD_REFERENCE
-#define EXPERIMENT_515_DONT_CACHE_REF
+#if defined(UNIT_TESTS)
 
 #endif
 
diff --git a/code/controllers/subsystem/garbage.dm b/code/controllers/subsystem/garbage.dm
index e94d6b1aff1d..37c305d59cde 100644
--- a/code/controllers/subsystem/garbage.dm
+++ b/code/controllers/subsystem/garbage.dm
@@ -139,13 +139,6 @@ SUBSYSTEM_DEF(garbage)
 			pass_counts[i] = 0
 			fail_counts[i] = 0
 
-#ifdef EXPERIMENT_515_QDEL_HARD_REFERENCE
-// 1 from the hard reference in the queue, and 1 from the variable used before this
-#define IS_DELETED(datum, _) (refcount(##datum) == 2)
-#else
-#define IS_DELETED(datum, gcd_at_time) (isnull(##datum) || ##datum.gc_destroyed != gcd_at_time)
-#endif
-
 /datum/controller/subsystem/garbage/proc/HandleQueue(level = GC_QUEUE_FILTER)
 	if (level == GC_QUEUE_FILTER)
 		delslasttick = 0
@@ -162,7 +155,7 @@ SUBSYSTEM_DEF(garbage)
 
 	lastlevel = level
 
-	//We do this rather then for(var/refID in queue) because that sort of for loop copies the whole list.
+	//We do this rather then for(var/list/ref_info in queue) because that sort of for loop copies the whole list.
 	//Normally this isn't expensive, but the gc queue can grow to 40k items, and that gets costly/causes overrun.
 	for (var/i in 1 to length(queue))
 		var/list/L = queue[i]
@@ -173,21 +166,15 @@ SUBSYSTEM_DEF(garbage)
 			continue
 
 		var/queued_at_time = L[GC_QUEUE_ITEM_QUEUE_TIME]
-
 		if(queued_at_time > cut_off_time)
 			break // Everything else is newer, skip them
 		count++
 
-#ifdef EXPERIMENT_515_QDEL_HARD_REFERENCE
 		var/datum/D = L[GC_QUEUE_ITEM_REF]
-#else
-		var/GCd_at_time = L[GC_QUEUE_ITEM_GCD_DESTROYED]
-		var/refID = L[GC_QUEUE_ITEM_REF]
-		var/datum/D
-		D = locate(refID)
-#endif
-
-		if (IS_DELETED(D, GCd_at_time)) // So if something else coincidently gets the same ref, it's not deleted by mistake
+
+		// 1 from the hard reference in the queue, and 1 from the variable used before this
+		// If that's all we've got, send er off
+		if (refcount(D) == 2)
 			++gcedlasttick
 			++totalgcs
 			pass_counts[level]++
@@ -221,11 +208,7 @@ SUBSYSTEM_DEF(garbage)
 				var/type = D.type
 				var/datum/qdel_item/I = items[type]
 
-				var/message = "## TESTING: GC: -- [text_ref(D)] | [type] was unable to be GC'd --"
-#if DM_VERSION >= 515
-				message = "[message] (ref count of [refcount(D)])"
-#endif
-				log_world(message)
+				log_world("## TESTING: GC: -- [text_ref(D)] | [type] was unable to be GC'd -- (ref count of [refcount(D)])")
 
 				#ifdef TESTING
 				for(var/c in GLOB.admins) //Using testing() here would fill the logs with ADMIN_VV garbage
@@ -261,8 +244,6 @@ SUBSYSTEM_DEF(garbage)
 		queue.Cut(1,count+1)
 		count = 0
 
-#undef IS_DELETED
-
 /datum/controller/subsystem/garbage/proc/Queue(datum/D, level = GC_QUEUE_FILTER)
 	if (isnull(D))
 		return
@@ -271,20 +252,11 @@ SUBSYSTEM_DEF(garbage)
 		return
 	var/queue_time = world.time
 
-#ifdef EXPERIMENT_515_QDEL_HARD_REFERENCE
-	var/refid = D
-#else
-	var/refid = text_ref(D)
-#endif
-
-	var/static/uid = 0
-	uid = WRAP(uid+1, 1, SHORT_REAL_LIMIT - 1)
 	if (D.gc_destroyed <= 0)
-		D.gc_destroyed = uid
+		D.gc_destroyed = queue_time
 
 	var/list/queue = queues[level]
-
-	queue[++queue.len] = list(queue_time, refid, D.gc_destroyed) // not += for byond reasons
+	queue[++queue.len] = list(queue_time, D, D.gc_destroyed) // not += for byond reasons
 
 //this is mainly to separate things profile wise.
 /datum/controller/subsystem/garbage/proc/HardDelete(datum/D, force)
diff --git a/code/datums/datum.dm b/code/datums/datum.dm
index 7d497785a72a..3e317ffd601e 100644
--- a/code/datums/datum.dm
+++ b/code/datums/datum.dm
@@ -54,13 +54,6 @@
 	*/
 	var/list/cooldowns
 
-#ifndef EXPERIMENT_515_DONT_CACHE_REF
-	/// A cached version of our \ref
-	/// The brunt of \ref costs are in creating entries in the string tree (a tree of immutable strings)
-	/// This avoids doing that more then once per datum by ensuring ref strings always have a reference to them after they're first pulled
-	var/cached_ref
-#endif
-
 	/// A weak reference to another datum
 	var/datum/weakref/weak_reference
 
diff --git a/code/game/machinery/autolathe.dm b/code/game/machinery/autolathe.dm
index cf7a0a6bc1a8..97a25bf7d20a 100644
--- a/code/game/machinery/autolathe.dm
+++ b/code/game/machinery/autolathe.dm
@@ -79,7 +79,7 @@
 							recipe.resources[material] = I.matter[material] //Doesn't take more if it's just a sheet or something. Get what you put in.
 						else
 							recipe.resources[material] = round(I.matter[material]*1.25) // More expensive to produce than they are to recycle.
-				qdel(I)
+			QDEL_NULL(I)
 
 	//Create parts for lathe.
 	for(var/component in components)
diff --git a/code/game/objects/items/devices/personal_data_transmitter.dm b/code/game/objects/items/devices/personal_data_transmitter.dm
index 98f8c60452ea..b967aa9273ca 100644
--- a/code/game/objects/items/devices/personal_data_transmitter.dm
+++ b/code/game/objects/items/devices/personal_data_transmitter.dm
@@ -139,6 +139,7 @@
 
 /obj/item/device/pdt_locator_tube/Destroy()
 	linked_bracelet = null
+	QDEL_NULL(battery)
 	return ..()
 
 /obj/item/clothing/accessory/pdt_bracelet
diff --git a/code/game/objects/items/reagent_containers/food/snacks.dm b/code/game/objects/items/reagent_containers/food/snacks.dm
index 79a108d24bf1..293a71ca7c5d 100644
--- a/code/game/objects/items/reagent_containers/food/snacks.dm
+++ b/code/game/objects/items/reagent_containers/food/snacks.dm
@@ -2744,6 +2744,10 @@
 	var/list/boxes = list() // If the boxes are stacked, they come here
 	var/boxtag = ""
 
+/obj/item/pizzabox/Destroy(force)
+	QDEL_NULL(pizza)
+	return ..()
+
 /obj/item/pizzabox/update_icon()
 
 	overlays = list()
diff --git a/code/game/objects/structures/pipes/pipes.dm b/code/game/objects/structures/pipes/pipes.dm
index 9f2b70c70661..fb51a605ee93 100644
--- a/code/game/objects/structures/pipes/pipes.dm
+++ b/code/game/objects/structures/pipes/pipes.dm
@@ -52,6 +52,7 @@
 
 	for(var/obj/structure/pipes/P in connected_to)
 		P.remove_connection(src)
+	connected_to.Cut()
 
 	GLOB.mainship_pipes -= src
 
@@ -96,6 +97,7 @@
 
 /obj/structure/pipes/proc/remove_connection(obj/structure/pipes/P)
 	connected_to -= P
+	P.connected_to -= src
 
 /obj/structure/pipes/proc/get_connection(direction)
 	var/obj/structure/pipes/best_connected_pipe = null
diff --git a/code/game/world.dm b/code/game/world.dm
index e55741ca71e5..5aecfe851051 100644
--- a/code/game/world.dm
+++ b/code/game/world.dm
@@ -14,7 +14,7 @@ GLOBAL_LIST_INIT(reboot_sfx, file2list("config/reboot_sfx.txt"))
 /world/New()
 	var/debug_server = world.GetConfig("env", "AUXTOOLS_DEBUG_DLL")
 	if (debug_server)
-		LIBCALL(debug_server, "auxtools_init")()
+		call_ext(debug_server, "auxtools_init")()
 		enable_debugging()
 	hub_password = "kMZy3U5jJHSiBQjr"
 
@@ -367,7 +367,7 @@ GLOBAL_LIST_INIT(reboot_sfx, file2list("config/reboot_sfx.txt"))
 		else
 			CRASH("unsupported platform")
 
-	var/init = LIBCALL(lib, "init")()
+	var/init = call_ext(lib, "init")()
 	if("0" != init)
 		CRASH("[lib] init error: [init]")
 
diff --git a/code/modules/admin/view_variables/reference_tracking.dm b/code/modules/admin/view_variables/reference_tracking.dm
index f6f2b86f31d7..35f464354c72 100644
--- a/code/modules/admin/view_variables/reference_tracking.dm
+++ b/code/modules/admin/view_variables/reference_tracking.dm
@@ -28,9 +28,7 @@
 
 	var/starting_time = world.time
 
-#if DM_VERSION >= 515
 	log_reftracker("Refcount for [type]: [refcount(src)]")
-#endif
 
 	//Time to search the whole game for our ref
 	DoSearchVar(GLOB, "GLOB", search_time = starting_time) //globals
diff --git a/code/modules/cm_phone/phone.dm b/code/modules/cm_phone/phone.dm
index b4f13044bc20..231bf54475d3 100644
--- a/code/modules/cm_phone/phone.dm
+++ b/code/modules/cm_phone/phone.dm
@@ -362,7 +362,7 @@ GLOBAL_LIST_EMPTY_TYPED(transmitters, /obj/structure/transmitter)
 			qdel(attached_to)
 		else
 			attached_to.attached_to = null
-			attached_to = null
+		attached_to = null
 
 	GLOB.transmitters -= src
 	SStgui.close_uis(src)
diff --git a/code/modules/projectiles/gun.dm b/code/modules/projectiles/gun.dm
index a9000eec5c28..a678ceda165c 100644
--- a/code/modules/projectiles/gun.dm
+++ b/code/modules/projectiles/gun.dm
@@ -503,13 +503,13 @@ As sniper rifles have both and weapon mods can change them as well. ..() deals w
 
 	if(slot in list(WEAR_L_HAND, WEAR_R_HAND))
 		set_gun_user(user)
-		if(HAS_TRAIT_FROM_ONLY(src, TRAIT_GUN_LIGHT_DEACTIVATED, user))
+		if(HAS_TRAIT_FROM_ONLY(src, TRAIT_GUN_LIGHT_DEACTIVATED, WEAKREF(user)))
 			force_light(on = TRUE)
-			REMOVE_TRAIT(src, TRAIT_GUN_LIGHT_DEACTIVATED, user)
+			REMOVE_TRAIT(src, TRAIT_GUN_LIGHT_DEACTIVATED, WEAKREF(user))
 	else
 		set_gun_user(null)
 		force_light(on = FALSE)
-		ADD_TRAIT(src, TRAIT_GUN_LIGHT_DEACTIVATED, user)
+		ADD_TRAIT(src, TRAIT_GUN_LIGHT_DEACTIVATED, WEAKREF(user))
 
 	return ..()
 
diff --git a/code/modules/projectiles/guns/specialist/launcher/launcher.dm b/code/modules/projectiles/guns/specialist/launcher/launcher.dm
index 70f00aa83c35..d0731b2d43bc 100644
--- a/code/modules/projectiles/guns/specialist/launcher/launcher.dm
+++ b/code/modules/projectiles/guns/specialist/launcher/launcher.dm
@@ -38,6 +38,10 @@
 			new preload(cylinder)
 		update_icon()
 
+/obj/item/weapon/gun/launcher/Destroy(force)
+	QDEL_NULL(cylinder)
+	return ..()
+
 /obj/item/weapon/gun/launcher/verb/toggle_draw_mode()
 	set name = "Switch Storage Drawing Method"
 	set category = "Object"
diff --git a/code/modules/reagents/chemistry_machinery/reagent_grinder.dm b/code/modules/reagents/chemistry_machinery/reagent_grinder.dm
index 1de4a84451e1..3c596b6a79a2 100644
--- a/code/modules/reagents/chemistry_machinery/reagent_grinder.dm
+++ b/code/modules/reagents/chemistry_machinery/reagent_grinder.dm
@@ -68,7 +68,10 @@
 
 /obj/structure/machinery/reagentgrinder/Destroy()
 	cleanup()
-	. = ..()
+
+	QDEL_NULL(beaker)
+
+	return ..()
 
 /obj/structure/machinery/reagentgrinder/update_icon()
 	icon_state = "juicer"+num2text(!isnull(beaker))
diff --git a/code/modules/vehicles/van/van.dm b/code/modules/vehicles/van/van.dm
index 8bf114d6b4a8..a2e7d68bf9de 100644
--- a/code/modules/vehicles/van/van.dm
+++ b/code/modules/vehicles/van/van.dm
@@ -167,6 +167,8 @@
 		var/mob/M = I
 		M.client.images -= normal_image
 
+	QDEL_NULL(lighting_holder)
+
 	return ..()
 
 
diff --git a/dependencies.sh b/dependencies.sh
index 69f16156b9d7..01d0ca5c976c 100644
--- a/dependencies.sh
+++ b/dependencies.sh
@@ -4,8 +4,8 @@
 #Final authority on what's required to fully build the project
 
 # byond version
-export BYOND_MAJOR=514
-export BYOND_MINOR=1588
+export BYOND_MAJOR=515
+export BYOND_MINOR=1627
 
 #rust_g git tag
 export RUST_G_VERSION=2.1.0
@@ -15,9 +15,7 @@ export NODE_VERSION=14
 export NODE_VERSION_PRECISE=14.16.1
 
 # SpacemanDMM git tag
-export SPACEMAN_DMM_VERSION=suite-1.7.2
+export SPACEMAN_DMM_VERSION=suite-1.8
 
 # Python version for mapmerge and other tools
 export PYTHON_VERSION=3.7.9
-
-export OPENDREAM_VERSION=tgs-min-compat
diff --git a/tools/build/build.js b/tools/build/build.js
index 2126cfd77d4c..9efee60ebd31 100644
--- a/tools/build/build.js
+++ b/tools/build/build.js
@@ -173,21 +173,30 @@ export const YarnTarget = new Juke.Target({
 export const TgFontTarget = new Juke.Target({
   dependsOn: [YarnTarget],
   inputs: [
-    'tgui/.yarn/install-target',
-    'tgui/packages/tgfont/**/*.+(js|cjs|svg)',
-    'tgui/packages/tgfont/package.json',
+    "tgui/.yarn/install-target",
+    "tgui/packages/tgfont/**/*.+(js|cjs|svg)",
+    "tgui/packages/tgfont/package.json",
   ],
   outputs: [
-    'tgui/packages/tgfont/dist/tgfont.css',
-    'tgui/packages/tgfont/dist/tgfont.eot',
-    'tgui/packages/tgfont/dist/tgfont.woff2',
+    "tgui/packages/tgfont/dist/tgfont.css",
+    "tgui/packages/tgfont/dist/tgfont.eot",
+    "tgui/packages/tgfont/dist/tgfont.woff2",
   ],
   executes: async () => {
-    await yarn('tgfont:build');
-    fs.copyFileSync('tgui/packages/tgfont/dist/tgfont.css', 'tgui/packages/tgfont/static/tgfont.css');
-    fs.copyFileSync('tgui/packages/tgfont/dist/tgfont.eot', 'tgui/packages/tgfont/static/tgfont.eot');
-    fs.copyFileSync('tgui/packages/tgfont/dist/tgfont.woff2', 'tgui/packages/tgfont/static/tgfont.woff2');
-  }
+    await yarn("tgfont:build");
+    fs.copyFileSync(
+      "tgui/packages/tgfont/dist/tgfont.css",
+      "tgui/packages/tgfont/static/tgfont.css"
+    );
+    fs.copyFileSync(
+      "tgui/packages/tgfont/dist/tgfont.eot",
+      "tgui/packages/tgfont/static/tgfont.eot"
+    );
+    fs.copyFileSync(
+      "tgui/packages/tgfont/dist/tgfont.woff2",
+      "tgui/packages/tgfont/static/tgfont.woff2"
+    );
+  },
 });
 
 export const TguiTarget = new Juke.Target({
@@ -303,8 +312,6 @@ export const CleanTarget = new Juke.Target({
   dependsOn: [TguiCleanTarget],
   executes: async () => {
     Juke.rm("*.{dmb,rsc}");
-    Juke.rm("*.mdme*");
-    Juke.rm("*.m.*");
     Juke.rm("maps/templates.dm");
   },
 });
diff --git a/tools/build/lib/byond.js b/tools/build/lib/byond.js
index 8b6f081c1c01..2d186e2254c6 100644
--- a/tools/build/lib/byond.js
+++ b/tools/build/lib/byond.js
@@ -139,14 +139,47 @@ export const DreamMaker = async (dmeFile, options = {}) => {
       throw err;
     }
   };
-  testOutputFile(`${dmeBaseName}.dmb`);
-  testOutputFile(`${dmeBaseName}.rsc`);
-  const runWithWarningChecks = async (dmeFile, args) => {
-    const execReturn = await Juke.exec(dmeFile, args);
+
+  const testDmVersion = async (dmPath) => {
+    const execReturn = await Juke.exec(dmPath, [], {
+      silent: true,
+      throw: false,
+    });
+    const version = execReturn.combined.match(
+      `DM compiler version (\\d+)\\.(\\d+)`
+    );
+    if (version == null) {
+      Juke.logger.error(
+        `Unexpected DreamMaker return, ensure "${dmPath}" is correct DM path.`
+      );
+      throw new Juke.ExitCode(1);
+    }
+    const requiredMajorVersion = 515;
+    const requiredMinorVersion = 1597; // First with -D switch functionality
+    const major = Number(version[1]);
+    const minor = Number(version[2]);
     if (
-      options.warningsAsErrors &&
-      execReturn.combined.match(/\d+:warning: /)
+      major < requiredMajorVersion ||
+      (major == requiredMajorVersion && minor < requiredMinorVersion)
     ) {
+      Juke.logger.error(
+        `${requiredMajorVersion}.${requiredMinorVersion} DM version required`
+      );
+      throw new Juke.ExitCode(1);
+    }
+  };
+
+  await testDmVersion(dmPath);
+  testOutputFile(`${dmeBaseName}.dmb`);
+  testOutputFile(`${dmeBaseName}.rsc`);
+  const runWithWarningChecks = async (dmPath, args) => {
+    const execReturn = await Juke.exec(dmPath, args);
+    const ignoredWarningCodes = options.ignoreWarningCodes ?? [];
+    const reg =
+      ignoredWarningCodes.length > 0
+        ? new RegExp(`\d+:warning: (?!(${ignoredWarningCodes.join("|")}))`)
+        : /\d+:warning: /;
+    if (options.warningsAsErrors && execReturn.combined.match(reg)) {
       Juke.logger.error(`Compile warnings treated as errors`);
       throw new Juke.ExitCode(2);
     }
@@ -156,26 +189,11 @@ export const DreamMaker = async (dmeFile, options = {}) => {
   const { defines } = options;
   if (defines && defines.length > 0) {
     Juke.logger.info("Using defines:", defines.join(", "));
-    try {
-      const injectedContent = defines.map((x) => `#define ${x}\n`).join("");
-      fs.writeFileSync(`${dmeBaseName}.m.dme`, injectedContent);
-      const dmeContent = fs.readFileSync(`${dmeBaseName}.dme`);
-      fs.appendFileSync(`${dmeBaseName}.m.dme`, dmeContent);
-      await runWithWarningChecks(dmPath, [`${dmeBaseName}.m.dme`]);
-      fs.writeFileSync(
-        `${dmeBaseName}.dmb`,
-        fs.readFileSync(`${dmeBaseName}.m.dmb`)
-      );
-      fs.writeFileSync(
-        `${dmeBaseName}.rsc`,
-        fs.readFileSync(`${dmeBaseName}.m.rsc`)
-      );
-    } finally {
-      Juke.rm(`${dmeBaseName}.m.*`);
-    }
-  } else {
-    await runWithWarningChecks(dmPath, [dmeFile]);
   }
+  await runWithWarningChecks(dmPath, [
+    ...defines.map((def) => `-D${def}`),
+    dmeFile,
+  ]);
 };
 
 /**