diff --git a/source/CMakeLists.txt b/source/CMakeLists.txt
index d7e77606d..040a7c92b 100644
--- a/source/CMakeLists.txt
+++ b/source/CMakeLists.txt
@@ -986,6 +986,7 @@ set (PCH_SOURCES
 	core/maphack.cpp
 	core/mapinfo.cpp
 	core/maploader.cpp
+	core/postprocessor.cpp
 	core/searchpaths.cpp
 	core/screenjob.cpp
 	core/initfs.cpp
diff --git a/source/core/postprocessor.cpp b/source/core/postprocessor.cpp
new file mode 100644
index 000000000..7a48052e7
--- /dev/null
+++ b/source/core/postprocessor.cpp
@@ -0,0 +1,103 @@
+/*
+** postprocessor.cpp
+** Level postprocessing
+**
+**---------------------------------------------------------------------------
+** Copyright 2009 Randy Heit
+** Copyright 2009-2018 Christoph Oelckers
+** Copyright 2019 Alexey Lysiuk
+** All rights reserved.
+**
+** Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions
+** are met:
+**
+** 1. Redistributions of source code must retain the above copyright
+**    notice, this list of conditions and the following disclaimer.
+** 2. Redistributions in binary form must reproduce the above copyright
+**    notice, this list of conditions and the following disclaimer in the
+**    documentation and/or other materials provided with the distribution.
+** 3. The name of the author may not be used to endorse or promote products
+**    derived from this software without specific prior written permission.
+**
+** THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+** IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+** INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+** NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+** THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+**---------------------------------------------------------------------------
+**
+*/
+#include "dobject.h"
+#include "vm.h"
+#include "printf.h"
+#include "types.h"
+
+//==========================================================================
+//
+// PostProcessLevel
+//
+//==========================================================================
+
+class DLevelPostProcessor : public DObject
+{
+	DECLARE_ABSTRACT_CLASS(DLevelPostProcessor, DObject)
+public:
+};
+
+IMPLEMENT_CLASS(DLevelPostProcessor, true, false);
+
+void PostProcessLevel(FName checksum, const FString& mapname)
+{
+	auto lc = Create<DLevelPostProcessor>();
+
+	for(auto cls : PClass::AllClasses)
+	{
+		if (cls->IsDescendantOf(RUNTIME_CLASS(DLevelPostProcessor)))
+		{
+			PFunction *const func = dyn_cast<PFunction>(cls->FindSymbol("Apply", false));
+			if (func == nullptr)
+			{
+				Printf("Missing 'Apply' method in class '%s', level compatibility object ignored\n", cls->TypeName.GetChars());
+				continue;
+			}
+
+			auto argTypes = func->Variants[0].Proto->ArgumentTypes;
+			if (argTypes.Size() != 3 || argTypes[1] != TypeName || argTypes[2] != TypeString)
+			{
+				Printf("Wrong signature of 'Apply' method in class '%s', level compatibility object ignored\n", cls->TypeName.GetChars());
+				continue;
+			}
+
+			VMValue param[] = { lc, checksum.GetIndex(), &mapname };
+			VMCall(func->Variants[0].Implementation, param, 3, nullptr, 0);
+		}
+	}
+}
+
+DEFINE_ACTION_FUNCTION(DLevelPostProcessor, SetSpriteLotag)
+{
+	PARAM_SELF_PROLOGUE(DLevelPostProcessor);
+	PARAM_INT(sprite);
+	PARAM_INT(lotag);
+	
+	// todo
+	return 0;
+}
+
+DEFINE_ACTION_FUNCTION(DLevelPostProcessor, ChangeSpriteFlags)
+{
+	PARAM_SELF_PROLOGUE(DLevelPostProcessor);
+	PARAM_INT(sprite);
+	PARAM_INT(clearmask);
+	PARAM_INT(setflag);
+
+	// todo
+	return 0;
+}
+
diff --git a/wadsrc/static/zscript.txt b/wadsrc/static/zscript.txt
index 9350ba327..29c05f07a 100644
--- a/wadsrc/static/zscript.txt
+++ b/wadsrc/static/zscript.txt
@@ -35,6 +35,8 @@ version "4.9"
 #include "zscript/usermapmenu.zs"
 #include "zscript/maptypes.zs"
 #include "zscript/coreactor.zs"
+#include "zscript/level_postprocessor.zs"
+#include "zscript/level_compatibility.zs"
 #include "zscript/alt_hud.zs"
 #include "zscript/games/duke/dukeactor.zs"
 #include "zscript/games/blood/bloodactor.zs"
diff --git a/wadsrc/static/zscript/level_compatibility.zs b/wadsrc/static/zscript/level_compatibility.zs
new file mode 100644
index 000000000..52192b199
--- /dev/null
+++ b/wadsrc/static/zscript/level_compatibility.zs
@@ -0,0 +1,12 @@
+
+class LevelCompatibility : LevelPostProcessor
+{
+	protected void Apply(Name checksum, String mapname)
+	{
+		switch (checksum)
+		{			
+			case 'none':
+				return;
+		}
+	}
+}
diff --git a/wadsrc/static/zscript/level_postprocessor.zs b/wadsrc/static/zscript/level_postprocessor.zs
new file mode 100644
index 000000000..9af905a9d
--- /dev/null
+++ b/wadsrc/static/zscript/level_postprocessor.zs
@@ -0,0 +1,10 @@
+
+class LevelPostProcessor native play
+{
+	protected void Apply(Name checksum, String mapname)
+	{
+	}
+
+	protected native void SetSpriteLotag(int sprite, int tag);
+	protected native void ChangeSpriteFlags(int sprite, int set, int clear);
+}