diff --git a/src/compatibility.cpp b/src/compatibility.cpp
index 7be7b4237c..52eb3aac40 100644
--- a/src/compatibility.cpp
+++ b/src/compatibility.cpp
@@ -466,7 +466,7 @@ void ParseCompatibility()
 //
 //==========================================================================
 
-void CheckCompatibility(MapData *map)
+FName CheckCompatibility(MapData *map)
 {
 	FMD5Holder md5;
 	FCompatValues *flags;
@@ -489,13 +489,16 @@ void CheckCompatibility(MapData *map)
 
 	flags = BCompatMap.CheckKey(md5);
 
+	FString hash;
+
+	for (size_t j = 0; j < sizeof(md5.Bytes); ++j)
+	{
+		hash.AppendFormat("%02X", md5.Bytes[j]);
+	}
+
 	if (developer >= DMSG_NOTIFY)
 	{
-		Printf("MD5 = ");
-		for (size_t j = 0; j < sizeof(md5.Bytes); ++j)
-		{
-			Printf("%02X", md5.Bytes[j]);
-		}
+		Printf("MD5 = %s", hash.GetChars());
 		if (flags != NULL)
 		{
 			Printf(", cflags = %08x, cflags2 = %08x, bflags = %08x\n",
@@ -523,6 +526,7 @@ void CheckCompatibility(MapData *map)
 	{
 		ib_compatflags |= BCOMPATF_FLOATBOB;
 	}
+	return FName(hash, true);	// if this returns NAME_None it means there is no scripted compatibility handler.
 }
 
 //==========================================================================
@@ -531,15 +535,19 @@ void CheckCompatibility(MapData *map)
 //
 //==========================================================================
 
-void SetCompatibilityParams()
+void SetCompatibilityParams(FName checksum)
 {
-	PClass *const cls = PClass::FindClass("LevelCompatibility");
-	if (cls != nullptr)
+	if (checksum != NAME_None)
 	{
-		PFunction *const func = dyn_cast<PFunction>(cls->FindSymbol("Apply", true));
-		if (func != nullptr)
+		PClass *const cls = PClass::FindClass("LevelCompatibility");
+		if (cls != nullptr)
 		{
-			VMCall(func->Variants[0].Implementation, nullptr, 0, nullptr, 0);
+			PFunction *const func = dyn_cast<PFunction>(cls->FindSymbol("Apply", true));
+			if (func != nullptr)
+			{
+				VMValue param = { (int)checksum };
+				VMCall(func->Variants[0].Implementation, &param, 1, nullptr, 0);
+			}
 		}
 	}
 
diff --git a/src/compatibility.h b/src/compatibility.h
index 125f83f34c..e219f5d0a0 100644
--- a/src/compatibility.h
+++ b/src/compatibility.h
@@ -36,7 +36,7 @@ struct FMD5HashTraits
 extern TMap<FMD5Holder, FCompatValues, FMD5HashTraits> BCompatMap;
 
 void ParseCompatibility();
-void CheckCompatibility(MapData *map);
-void SetCompatibilityParams();
+FName CheckCompatibility(MapData *map);
+void SetCompatibilityParams(FName);
 
 #endif
diff --git a/src/p_setup.cpp b/src/p_setup.cpp
index 648502542a..6f84da6d96 100644
--- a/src/p_setup.cpp
+++ b/src/p_setup.cpp
@@ -3756,7 +3756,7 @@ void P_SetupLevel (const char *lumpname, int position)
 		{
 			level.maptype = MAPTYPE_UDMF;
 		}
-		CheckCompatibility(map);
+		FName checksum = CheckCompatibility(map);
 		if (ib_compatflags & BCOMPATF_REBUILDNODES)
 		{
 			ForceNodeBuild = true;
@@ -3834,7 +3834,7 @@ void P_SetupLevel (const char *lumpname, int position)
 			times[0].Unclock();
 		}
 
-		SetCompatibilityParams();
+		SetCompatibilityParams(checksum);
 
 		times[6].Clock();
 		P_LoopSidedefs (true);
diff --git a/wadsrc/static/zscript/level_compatibility.txt b/wadsrc/static/zscript/level_compatibility.txt
index 17bddba134..7b446370a9 100644
--- a/wadsrc/static/zscript/level_compatibility.txt
+++ b/wadsrc/static/zscript/level_compatibility.txt
@@ -1,24 +1,28 @@
 
 class LevelCompatibility play
 {
-	private static void Apply()
+	private static void Apply(Name checksum)
 	{
-		string checksum = level.GetChecksum();
-
-		if (   checksum ~== "AB24AE6E2CB13CBDD04600A4D37F9189"   // doom2.wad map02
-			|| checksum ~== "1EC0AF1E3985650F0C9000319C599D0C")  // doom2bfg.wad map02
+		switch (checksum)
 		{
-			// Missing textures
-			TextureID stone4 = TexMan.CheckForTexture("STONE4", TexMan.Type_Wall);
-			SetWallTextureID(327, Line.front, Side.bottom, stone4);
-			SetWallTextureID(328, Line.front, Side.bottom, stone4);
-			SetWallTextureID(338, Line.front, Side.bottom, stone4);
-			SetWallTextureID(339, Line.front, Side.bottom, stone4);
-		}
-		else if (checksum ~== "66C46385EB1A23D60839D1532522076B")  // doom2.wad map08
-		{
-			// Missing texture
-			SetWallTexture(101, Line.back, Side.top, "BRICK7");
+			case 'AB24AE6E2CB13CBDD04600A4D37F9189':   // doom2.wad map02
+			case '1EC0AF1E3985650F0C9000319C599D0C':  // doom2bfg.wad map02
+			{
+				// Missing textures
+				TextureID stone4 = TexMan.CheckForTexture("STONE4", TexMan.Type_Wall);
+				SetWallTextureID(327, Line.front, Side.bottom, stone4);
+				SetWallTextureID(328, Line.front, Side.bottom, stone4);
+				SetWallTextureID(338, Line.front, Side.bottom, stone4);
+				SetWallTextureID(339, Line.front, Side.bottom, stone4);
+				break;
+			}
+			
+			case '66C46385EB1A23D60839D1532522076B':  // doom2.wad map08
+			{
+				// Missing texture
+				SetWallTexture(101, Line.back, Side.top, "BRICK7");
+				break;
+			}
 		}
 	}