diff --git a/code/__DEFINES/atmospherics.dm b/code/__DEFINES/atmospherics.dm
index e4f00165e4..3f99b4446a 100644
--- a/code/__DEFINES/atmospherics.dm
+++ b/code/__DEFINES/atmospherics.dm
@@ -281,12 +281,13 @@ GLOBAL_LIST_INIT(atmos_adjacent_savings, list(0,0))
 #define CALCULATE_ADJACENT_TURFS(T) SSadjacent_air.queue[T] = 1
 #endif
 
+#define EXTOOLS (world.system_type == MS_WINDOWS ? "byond-extools.dll" : "libbyond-extools.so")
+
 GLOBAL_VAR(atmos_extools_initialized) // this must be an uninitialized (null) one or init_monstermos will be called twice because reasons
 #define ATMOS_EXTOOLS_CHECK if(!GLOB.atmos_extools_initialized){\
 	GLOB.atmos_extools_initialized=TRUE;\
-	var/extools = world.GetConfig("env", "EXTOOLS_DLL") || "./byond-extools.dll";\
-	if(fexists(extools)){\
-		var/result = call(extools,"init_monstermos")();\
+	if(fexists(EXTOOLS)){\
+		var/result = call(EXTOOLS,"init_monstermos")();\
 		if(result != "ok") {CRASH(result);}\
 	} else {\
 		CRASH("byond-extools.dll does not exist!");\