diff --git a/src/actor.h b/src/actor.h
index ed38d0020..f8545624a 100644
--- a/src/actor.h
+++ b/src/actor.h
@@ -1048,6 +1048,7 @@ 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 6c8652f7c..78a27c95d 100644
--- a/src/g_strife/a_rebels.cpp
+++ b/src/g_strife/a_rebels.cpp
@@ -85,7 +85,7 @@ 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 ae456883c..c0fbf4630 100644
--- a/src/namedef.h
+++ b/src/namedef.h
@@ -298,6 +298,8 @@ 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 0c61b2d7d..57c7cdfa0 100644
--- a/src/p_interaction.cpp
+++ b/src/p_interaction.cpp
@@ -1516,7 +1516,7 @@ dopain:
 	{
 		if (source == target->target)
 		{
-			target->threshold = BASETHRESHOLD;
+			target->threshold = target->DefThreshold; //BASETHRESHOLD is no longer used here.
 			if (target->state == target->SpawnState && target->SeeState != NULL)
 			{
 				target->SetState (target->SeeState);
@@ -1537,7 +1537,7 @@ 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 395a05990..79050472a 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 789c468d1..317af441c 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -348,6 +348,10 @@ void AActor::Serialize (FArchive &arc)
 			<< RipLevelMin
 			<< RipLevelMax;
 	}
+	if (SaveVersion >= 4531)
+	{
+		arc << DefThreshold;
+	}
 
 	{
 		FString tagstr;
diff --git a/src/thingdef/thingdef_codeptr.cpp b/src/thingdef/thingdef_codeptr.cpp
index 8608915f4..ba584f5b7 100644
--- a/src/thingdef/thingdef_codeptr.cpp
+++ b/src/thingdef/thingdef_codeptr.cpp
@@ -6028,6 +6028,33 @@ DEFINE_ACTION_FUNCTION_PARAMS(AActor, A_SetRipMax)
 	self->RipLevelMax = max;
 }
 
+//===========================================================================
+//
+// 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)
+{
+	ACTION_PARAM_START(3);
+	ACTION_PARAM_INT(threshold, 0);
+	ACTION_PARAM_BOOL(def, 1);
+	ACTION_PARAM_INT(ptr, 2);
+
+	AActor *mobj = COPY_AAPTR(self, ptr);
+	if (!mobj)
+	{
+		ACTION_SET_RESULT(false);
+		return;
+	}
+	if (def)
+		mobj->DefThreshold = (threshold >= 0) ? threshold : 0;
+	else
+		mobj->threshold = (threshold >= 0) ? threshold : 0;
+}
+
 //==========================================================================
 //
 // A_CheckProximity(jump, classname, distance, count, flags, ptr)
diff --git a/src/thingdef/thingdef_expression.cpp b/src/thingdef/thingdef_expression.cpp
index 6267ae6d9..7abc00925 100644
--- a/src/thingdef/thingdef_expression.cpp
+++ b/src/thingdef/thingdef_expression.cpp
@@ -90,7 +90,8 @@ DEFINE_MEMBER_VARIABLE(reactiontime, AActor)
 DEFINE_MEMBER_VARIABLE(meleerange, AActor)
 DEFINE_MEMBER_VARIABLE(Speed, AActor)
 DEFINE_MEMBER_VARIABLE(roll, AActor)
-
+DEFINE_MEMBER_VARIABLE(threshold, AActor)
+DEFINE_MEMBER_VARIABLE(DefThreshold, AActor)
 
 //==========================================================================
 //
diff --git a/src/thingdef/thingdef_properties.cpp b/src/thingdef/thingdef_properties.cpp
index fd0636a70..0f6b302aa 100644
--- a/src/thingdef/thingdef_properties.cpp
+++ b/src/thingdef/thingdef_properties.cpp
@@ -532,6 +532,17 @@ 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 167f8a303..34e7c22f7 100644
--- a/src/version.h
+++ b/src/version.h
@@ -75,8 +75,8 @@ const char *GetVersionString();
 #define MINSAVEVER	3100
 
 // Use 4500 as the base git save version, since it's higher than the
-// SVN revision ever got.
-#define SAVEVER 4531
+// SVN revision ever got.
+#define SAVEVER 4532
 
 #define SAVEVERSTRINGIFY2(x) #x
 #define SAVEVERSTRINGIFY(x) SAVEVERSTRINGIFY2(x)
diff --git a/wadsrc/static/actors/actor.txt b/wadsrc/static/actors/actor.txt
index 08e376e61..8bc4f6dc2 100644
--- a/wadsrc/static/actors/actor.txt
+++ b/wadsrc/static/actors/actor.txt
@@ -31,6 +31,7 @@ ACTOR Actor native //: Thinker
 	RipperLevel 0
 	RipLevelMin 0
 	RipLevelMax 0
+	ChaseThreshold 100
 
 	// Variables for the expression evaluator
 	// NOTE: fixed_t and angle_t are only used here to ensure proper conversion
@@ -69,6 +70,8 @@ ACTOR Actor native //: Thinker
 	native fixed_t meleerange;
 	native fixed_t speed;
 	native angle_t roll;
+	native int threshold;
+	native int DefThreshold;
 
 	// Meh, MBF redundant functions. Only for DeHackEd support.
 	action native A_Turn(float angle = 0);
@@ -339,7 +342,8 @@ 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);