diff --git a/src/actor.h b/src/actor.h
index 86bfd9796..e6ae8d9f8 100644
--- a/src/actor.h
+++ b/src/actor.h
@@ -1041,6 +1041,7 @@ public:
 	SDWORD			reactiontime;	// if non 0, don't attack yet; used by
 									// player to freeze a bit after teleporting
 	SDWORD			threshold;		// if > 0, the target will be chased
+	SDWORD			DefThreshold;	// [MC] Default threshold which the actor will reset its threshold to after switching targets
 									// no matter what (even if shot)
 	player_t		*player;		// only valid if type of APlayerPawn
 	TObjPtr<AActor>	LastLookActor;	// Actor last looked for (if TIDtoHate != 0)
diff --git a/src/g_strife/a_rebels.cpp b/src/g_strife/a_rebels.cpp
index 26d46cffc..f78f38d43 100644
--- a/src/g_strife/a_rebels.cpp
+++ b/src/g_strife/a_rebels.cpp
@@ -90,7 +90,7 @@ DEFINE_ACTION_FUNCTION(AActor, A_Beacon)
 	self->flags &= ~MF_SPECIAL;
 	static_cast<AInventory *>(self)->DropTime = 0;
 	// Set up the new rebel.
-	rebel->threshold = BASETHRESHOLD;
+	rebel->threshold = rebel->DefThreshold;
 	rebel->target = NULL;
 	rebel->flags4 |= MF4_INCOMBAT;
 	rebel->LastHeard = owner;	// Make sure the rebels look for targets
diff --git a/src/namedef.h b/src/namedef.h
index d06ca9ccc..e7af23025 100644
--- a/src/namedef.h
+++ b/src/namedef.h
@@ -300,6 +300,8 @@ xx(Z)
 xx(MomX)
 xx(MomY)
 xx(MomZ)
+xx(Threshold)
+xx(DefThreshold)
 xx(Abs)
 xx(ACS_NamedExecuteWithResult)
 xx(CallACS)
diff --git a/src/p_interaction.cpp b/src/p_interaction.cpp
index b97d17af8..eb3c6d354 100644
--- a/src/p_interaction.cpp
+++ b/src/p_interaction.cpp
@@ -1511,7 +1511,7 @@ dopain:
 	{
 		if (source == target->target)
 		{
-			target->threshold = BASETHRESHOLD;
+			target->threshold = target->DefThreshold;
 			if (target->state == target->SpawnState && target->SeeState != NULL)
 			{
 				target->SetState (target->SeeState);
@@ -1532,7 +1532,7 @@ dopain:
 				target->lastenemy = target->target; // remember last enemy - killough
 			}
 			target->target = source;
-			target->threshold = BASETHRESHOLD;
+			target->threshold = target->DefThreshold;
 			if (target->state == target->SpawnState && target->SeeState != NULL)
 			{
 				target->SetState (target->SeeState);
diff --git a/src/p_local.h b/src/p_local.h
index 1064abbf9..9030a0736 100644
--- a/src/p_local.h
+++ b/src/p_local.h
@@ -87,7 +87,8 @@ inline int GetSafeBlockY(long long blocky)
 #define PLAYERMISSILERANGE	(8192*FRACUNIT)	// [RH] New MISSILERANGE for players
 
 // follow a player exlusively for 3 seconds
-#define BASETHRESHOLD	100
+// No longer used.
+// #define BASETHRESHOLD	100
 
 
 //
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index 562128542..d47460038 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -433,6 +433,10 @@ void AActor::Serialize (FArchive &arc)
 			<< RipLevelMin
 			<< RipLevelMax;
 	}
+	if (SaveVersion >= 4533)
+	{
+		arc << DefThreshold;
+	}
 
 	{
 		FString tagstr;
diff --git a/src/p_saveg.cpp b/src/p_saveg.cpp
index f0aedd5c6..cf2be64e8 100644
--- a/src/p_saveg.cpp
+++ b/src/p_saveg.cpp
@@ -516,7 +516,7 @@ void P_SerializeWorld (FArchive &arc)
 		arc << zn->Environment;
 	}
 
-	if (SaveVersion >= 4532)
+	if (SaveVersion >= 4533)
 	{
 		arc << linePortals;
 	}
diff --git a/src/thingdef/thingdef_codeptr.cpp b/src/thingdef/thingdef_codeptr.cpp
index 70a6d96ec..22146228d 100644
--- a/src/thingdef/thingdef_codeptr.cpp
+++ b/src/thingdef/thingdef_codeptr.cpp
@@ -6360,6 +6360,35 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetRipMax)
 	return 0;
 }
 
+//===========================================================================
+//
+// A_SetChaseThreshold(int threshold, bool def, int ptr)
+//
+// Sets the current chase threshold of the actor (pointer). If def is true,
+// changes the default threshold which the actor resets to once it switches
+// targets and doesn't have the +QUICKTORETALIATE flag.
+//===========================================================================
+DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetChaseThreshold)
+{
+	PARAM_ACTION_PROLOGUE;
+	PARAM_INT(threshold);
+	PARAM_BOOL_OPT(def) { def = false; }
+	PARAM_INT_OPT(ptr) { ptr = AAPTR_DEFAULT; }
+
+
+	AActor *mobj = COPY_AAPTR(self, ptr);
+	if (!mobj)
+	{
+		ACTION_SET_RESULT(false);
+		return 0;
+	}
+	if (def)
+		mobj->DefThreshold = (threshold >= 0) ? threshold : 0;
+	else
+		mobj->threshold = (threshold >= 0) ? threshold : 0;
+	return 0;
+}
+
 //==========================================================================
 //
 // A_CheckProximity(jump, classname, distance, count, flags, ptr)
@@ -6687,4 +6716,4 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_FaceMovementDirection)
 		}
 	}
 	return numret;
-}
\ No newline at end of file
+}
diff --git a/src/thingdef/thingdef_data.cpp b/src/thingdef/thingdef_data.cpp
index 8581ca8b2..82fe3a739 100644
--- a/src/thingdef/thingdef_data.cpp
+++ b/src/thingdef/thingdef_data.cpp
@@ -651,4 +651,6 @@ void InitThingdef()
 	symt.AddSymbol(new PField(NAME_ReactionTime,TypeSInt32,	VARF_Native, myoffsetof(AActor,reactiontime)));
 	symt.AddSymbol(new PField(NAME_MeleeRange,	TypeFixed,	VARF_Native, myoffsetof(AActor,meleerange)));
 	symt.AddSymbol(new PField(NAME_Speed,		TypeFixed,	VARF_Native, myoffsetof(AActor,Speed)));
+	symt.AddSymbol(new PField(NAME_Threshold,	TypeSInt32, VARF_Native, myoffsetof(AActor,threshold)));
+	symt.AddSymbol(new PField(NAME_DefThreshold,TypeSInt32, VARF_Native, myoffsetof(AActor,DefThreshold)));
 }
diff --git a/src/thingdef/thingdef_properties.cpp b/src/thingdef/thingdef_properties.cpp
index fef2c075a..5b9874a35 100644
--- a/src/thingdef/thingdef_properties.cpp
+++ b/src/thingdef/thingdef_properties.cpp
@@ -544,6 +544,17 @@ DEFINE_PROPERTY(painthreshold, I, Actor)
 	defaults->PainThreshold = id;
 }
 
+//==========================================================================
+//
+//==========================================================================
+DEFINE_PROPERTY(chasethreshold, I, Actor)
+{
+	PROP_INT_PARM(id, 0);
+	if (id < 0)
+		I_Error("ChaseThreshold cannot be negative.");
+	defaults->DefThreshold = id;
+}
+
 //==========================================================================
 //
 //==========================================================================
diff --git a/src/version.h b/src/version.h
index 3af1c1b7f..a585e9aec 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 4532
+#define SAVEVER 4533
 
 #define SAVEVERSTRINGIFY2(x) #x
 #define SAVEVERSTRINGIFY(x) SAVEVERSTRINGIFY2(x)
diff --git a/wadsrc/static/actors/actor.txt b/wadsrc/static/actors/actor.txt
index 1f7efd895..869d9dd2e 100644
--- a/wadsrc/static/actors/actor.txt
+++ b/wadsrc/static/actors/actor.txt
@@ -31,13 +31,13 @@ ACTOR Actor native //: Thinker
 	RipperLevel 0
 	RipLevelMin 0
 	RipLevelMax 0
-
+	ChaseThreshold 100
+
 	// Functions
 	native bool CheckClass(class<Actor> checkclass, int ptr_select = AAPTR_DEFAULT, bool match_superclass = false);
 	native bool IsPointerEqual(int ptr_select1, int ptr_select2);
 
 	// Action functions
-
 	// Meh, MBF redundant functions. Only for DeHackEd support.
 	action native A_Turn(float angle = 0);
 	action native A_LineEffect(int boomspecial = 0, int tag = 0);
@@ -307,7 +307,8 @@ ACTOR Actor native //: Thinker
 	action native A_SetRipperLevel(int level);
 	action native A_SetRipMin(int min);
 	action native A_SetRipMax(int max);
-	action native A_CheckProximity(state jump, class<Actor> classname, float distance, int count = 1, int flags = 0, int ptr = AAPTR_DEFAULT);
+	action native A_SetChaseThreshold(int threshold, bool def = false, int ptr = AAPTR_DEFAULT);
+	action native A_CheckProximity(state jump, class<Actor> classname, float distance, int count = 1, int flags = 0, int ptr = AAPTR_DEFAULT);
 	action native A_CheckBlock(state block, int flags = 0, int ptr = AAPTR_DEFAULT);
 	action native A_CheckSightOrRange(float distance, state label, bool two_dimension = false);
 	action native A_CheckRange(float distance, state label, bool two_dimension = false);