diff --git a/src/actor.h b/src/actor.h
index 1d1090c19..7ef63bb94 100644
--- a/src/actor.h
+++ b/src/actor.h
@@ -976,7 +976,6 @@ public:
 	DVector3		OldRenderPos;
 
 	DRotator		Angles;
-	DAngle			FlatAngle;
 	DVector3		Vel;
 	double			Speed;
 	double			FloatSpeed;
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index e51a62856..b7d887195 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -263,10 +263,6 @@ void AActor::Serialize(FArchive &arc)
 		<< Vel
 		<< tics
 		<< state;
-	if (SaveVersion >= 4546)
-	{
-		arc << FlatAngle;
-	}
 	if (arc.IsStoring())
 	{
 		int dmg;
diff --git a/src/thingdef/thingdef_codeptr.cpp b/src/thingdef/thingdef_codeptr.cpp
index 20848f478..9b8975063 100644
--- a/src/thingdef/thingdef_codeptr.cpp
+++ b/src/thingdef/thingdef_codeptr.cpp
@@ -6882,24 +6882,3 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_FaceMovementDirection)
 	ACTION_RETURN_BOOL(true);
 }
 
-//===========================================================================
-//
-// A_SetFlatAngle
-//
-// Set actor's flat angle (in degrees). GZDoom only. Requires the 
-// (PITCH)FLATSPRITE flag to have any visible effect.
-//
-//===========================================================================
-DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetFlatAngle)
-{
-	PARAM_ACTION_PROLOGUE;
-	PARAM_FLOAT_OPT(flatangle) { flatangle = 0; }
-	PARAM_INT_OPT(ptr) { ptr = AAPTR_DEFAULT; }
-	
-	AActor *ref = COPY_AAPTR(self, ptr);
-	if (ref != NULL)
-	{
-		ref->FlatAngle = flatangle;
-	}
-	return 0;
-}
\ No newline at end of file
diff --git a/src/thingdef/thingdef_data.cpp b/src/thingdef/thingdef_data.cpp
index 9669c78ab..8b245e828 100644
--- a/src/thingdef/thingdef_data.cpp
+++ b/src/thingdef/thingdef_data.cpp
@@ -627,7 +627,6 @@ void InitThingdef()
 	PType *array5 = NewArray(TypeSInt32, 5);
 	symt.AddSymbol(new PField(NAME_Alpha,		TypeFloat64,	VARF_Native, myoffsetof(AActor,Alpha)));
 	symt.AddSymbol(new PField(NAME_Angle,		TypeFloat64,	VARF_Native, myoffsetof(AActor,Angles.Yaw)));
-	symt.AddSymbol(new PField(NAME_FlatAngle,	TypeFloat64,	VARF_Native, myoffsetof(AActor,FlatAngle)));
 	symt.AddSymbol(new PField(NAME_Args,		array5,			VARF_Native, myoffsetof(AActor,args)));
 	symt.AddSymbol(new PField(NAME_CeilingZ,	TypeFloat64,	VARF_Native, myoffsetof(AActor,ceilingz)));
 	symt.AddSymbol(new PField(NAME_FloorZ,		TypeFloat64,	VARF_Native, myoffsetof(AActor,floorz)));
diff --git a/src/thingdef/thingdef_properties.cpp b/src/thingdef/thingdef_properties.cpp
index 7bf72fc48..3ec4c624d 100644
--- a/src/thingdef/thingdef_properties.cpp
+++ b/src/thingdef/thingdef_properties.cpp
@@ -682,15 +682,6 @@ DEFINE_PROPERTY(scale, F, Actor)
 	defaults->Scale.X = defaults->Scale.Y = id;
 }
 
-//==========================================================================
-//
-//==========================================================================
-DEFINE_PROPERTY(flatangle, F, Actor)
-{
-	PROP_DOUBLE_PARM(id, 0);
-	defaults->FlatAngle = id;
-}
-
 //==========================================================================
 //
 //==========================================================================
diff --git a/src/version.h b/src/version.h
index 52b7ea0ba..21d05b3ed 100644
--- a/src/version.h
+++ b/src/version.h
@@ -76,7 +76,7 @@ const char *GetVersionString();
 
 // Use 4500 as the base git save version, since it's higher than the
 // SVN revision ever got.
-#define SAVEVER 4546
+#define SAVEVER 4545
 
 #define SAVEVERSTRINGIFY2(x) #x
 #define SAVEVERSTRINGIFY(x) SAVEVERSTRINGIFY2(x)
diff --git a/wadsrc/static/actors/actor.txt b/wadsrc/static/actors/actor.txt
index 8794debde..6129d9b9b 100644
--- a/wadsrc/static/actors/actor.txt
+++ b/wadsrc/static/actors/actor.txt
@@ -34,9 +34,7 @@ ACTOR Actor native //: Thinker
 	DefThreshold 100
 	BloodType "Blood", "BloodSplatter", "AxeBlood"
 	ExplosionDamage 128
-	MissileHeight 32
-	FlatAngle 0
-	
+	MissileHeight 32	
 
 	// Functions
 	native bool CheckClass(class<Actor> checkclass, int ptr_select = AAPTR_DEFAULT, bool match_superclass = false);
@@ -326,7 +324,6 @@ ACTOR Actor native //: Thinker
 	native state A_CheckSightOrRange(float distance, state label, bool two_dimension = false);
 	native state A_CheckRange(float distance, state label, bool two_dimension = false);
 	action native bool A_FaceMovementDirection(float offset = 0, float anglelimit = 0, float pitchlimit = 0, int flags = 0, int ptr = AAPTR_DEFAULT);
-	action native A_SetFlatAngle(float flatangle = 0, int ptr = AAPTR_DEFAULT);
 
 	native void A_RearrangePointers(int newtarget, int newmaster = AAPTR_DEFAULT, int newtracer = AAPTR_DEFAULT, int flags=0);
 	native void A_TransferPointer(int ptr_source, int ptr_recepient, int sourcefield, int recepientfield=AAPTR_DEFAULT, int flags=0);