diff --git a/baystation12.dme b/baystation12.dme
index e3e3f12ee1..a7f8a4defa 100644
--- a/baystation12.dme
+++ b/baystation12.dme
@@ -198,6 +198,7 @@
 #include "code\datums\wires\suit_storage_unit.dm"
 #include "code\datums\wires\vending.dm"
 #include "code\datums\wires\wires.dm"
+#include "code\defines\gases.dm"
 #include "code\defines\obj.dm"
 #include "code\defines\obj\weapon.dm"
 #include "code\defines\procs\admin.dm"
@@ -1697,6 +1698,8 @@
 #include "code\modules\virus2\helpers.dm"
 #include "code\modules\virus2\isolator.dm"
 #include "code\modules\virus2\items_devices.dm"
+#include "code\modules\xgm\xgm_gas_data.dm"
+#include "code\modules\xgm\xgm_gas_mixture.dm"
 #include "code\TriDimension\controller.dm"
 #include "code\TriDimension\controller_presets.dm"
 #include "code\TriDimension\Movement.dm"
@@ -1705,8 +1708,6 @@
 #include "code\TriDimension\Structures_presets.dm"
 #include "code\TriDimension\Turfs.dm"
 #include "code\ZAS\_docs.dm"
-#include "code\ZAS\_gas_mixture_xgm.dm"
-#include "code\ZAS\_xgm_gas_data.dm"
 #include "code\ZAS\Airflow.dm"
 #include "code\ZAS\Atom.dm"
 #include "code\ZAS\Connection.dm"
@@ -1716,7 +1717,6 @@
 #include "code\ZAS\Debug.dm"
 #include "code\ZAS\Diagnostic.dm"
 #include "code\ZAS\Fire.dm"
-#include "code\ZAS\Gas.dm"
 #include "code\ZAS\Phoron.dm"
 #include "code\ZAS\Turf.dm"
 #include "code\ZAS\Variable Settings.dm"
diff --git a/code/ZAS/Gas.dm b/code/defines/gases.dm
similarity index 83%
rename from code/ZAS/Gas.dm
rename to code/defines/gases.dm
index 0f3faa09b4..1f8c871ad3 100644
--- a/code/ZAS/Gas.dm
+++ b/code/defines/gases.dm
@@ -1,4 +1,4 @@
-/xgm_gas/oxygen
+/decl/xgm_gas/oxygen
 	id = "oxygen"
 	name = "Oxygen"
 	specific_heat = 20	// J/(mol*K)
@@ -6,19 +6,19 @@
 
 	flags = XGM_GAS_OXIDIZER
 
-/xgm_gas/nitrogen
+/decl/xgm_gas/nitrogen
 	id = "nitrogen"
 	name = "Nitrogen"
 	specific_heat = 20	// J/(mol*K)
 	molar_mass = 0.028	// kg/mol
 
-/xgm_gas/carbon_dioxide
+/decl/xgm_gas/carbon_dioxide
 	id = "carbon_dioxide"
 	name = "Carbon Dioxide"
 	specific_heat = 30	// J/(mol*K)
 	molar_mass = 0.044	// kg/mol
 
-/xgm_gas/phoron
+/decl/xgm_gas/phoron
 	id = "phoron"
 	name = "Phoron"
 	specific_heat = 200	// J/(mol*K)
@@ -32,7 +32,7 @@
 	overlay_limit = 0.7
 	flags = XGM_GAS_FUEL | XGM_GAS_CONTAMINANT
 
-/xgm_gas/volatile_fuel
+/decl/xgm_gas/volatile_fuel
 	id = "volatile_fuel"
 	name = "Volatile Fuel"
 	specific_heat = 253	// J/(mol*K)	C8H18 gasoline. Isobaric, but good enough.
@@ -40,7 +40,7 @@
 
 	flags = XGM_GAS_FUEL
 
-/xgm_gas/sleeping_agent
+/decl/xgm_gas/sleeping_agent
 	id = "sleeping_agent"
 	name = "Sleeping Agent"
 	specific_heat = 40	// J/(mol*K)
@@ -49,7 +49,7 @@
 	tile_overlay = "sleeping_agent"
 	overlay_limit = 1
 
-/xgm_gas/oxygen_agent_b
+/decl/xgm_gas/oxygen_agent_b
 	id = "oxygen_agent_b"
 	name = "Oxygen Agent-B"	//what is this?
 	specific_heat = 300	// J/(mol*K)
diff --git a/code/ZAS/_xgm_gas_data.dm b/code/modules/xgm/xgm_gas_data.dm
similarity index 83%
rename from code/ZAS/_xgm_gas_data.dm
rename to code/modules/xgm/xgm_gas_data.dm
index fd732f9d7c..4ee3e1c501 100644
--- a/code/ZAS/_xgm_gas_data.dm
+++ b/code/modules/xgm/xgm_gas_data.dm
@@ -1,6 +1,6 @@
-/var/xgm_gas_data/gas_data
+/var/datum/xgm_gas_data/gas_data
 
-/xgm_gas_data
+/datum/xgm_gas_data
 	//Simple list of all the gas IDs.
 	var/list/gases = list()
 	//The friendly, human-readable name for the gas.
@@ -16,7 +16,7 @@
 	//Flags.
 	var/list/flags = list()
 
-/xgm_gas
+/decl/xgm_gas
 	var/id = ""
 	var/name = "Unnamed Gas"
 	var/specific_heat = 20	// J/(mol*K)
@@ -29,8 +29,8 @@
 
 /hook/startup/proc/generateGasData()
 	gas_data = new
-	for(var/p in (typesof(/xgm_gas) - /xgm_gas))
-		var/xgm_gas/gas = new p
+	for(var/p in (typesof(/decl/xgm_gas) - /decl/xgm_gas))
+		var/decl/xgm_gas/gas = new p //avoid initial() because of potential New() actions
 
 		if(gas.id in gas_data.gases)
 			error("Duplicate gas id `[gas.id]` in `[p]`")
diff --git a/code/ZAS/_gas_mixture_xgm.dm b/code/modules/xgm/xgm_gas_mixture.dm
similarity index 96%
rename from code/ZAS/_gas_mixture_xgm.dm
rename to code/modules/xgm/xgm_gas_mixture.dm
index 8043be1579..5806237d04 100644
--- a/code/ZAS/_gas_mixture_xgm.dm
+++ b/code/modules/xgm/xgm_gas_mixture.dm
@@ -1,5 +1,3 @@
-#define QUANTIZE(variable)		(round(variable,0.0001))
-
 /datum/gas_mixture
 	//Associative list of gas moles.
 	//Gases with 0 moles are not tracked and are pruned by update_values()
diff --git a/code/setup.dm b/code/setup.dm
index 4df34404a5..4ffbf59800 100644
--- a/code/setup.dm
+++ b/code/setup.dm
@@ -963,6 +963,7 @@ var/list/be_special_flags = list(
 #define WALL_OPENING 2
 
 #define CLAMP01(x) max(0, min(1, x))
+#define QUANTIZE(variable) (round(variable,0.0001))
 
 #define DEFAULT_WALL_MATERIAL "steel"