diff --git a/src/p_actionfunctions.cpp b/src/p_actionfunctions.cpp
index 8c222a4f6..13a347ef2 100644
--- a/src/p_actionfunctions.cpp
+++ b/src/p_actionfunctions.cpp
@@ -6852,13 +6852,27 @@ DEFINE_ACTION_FUNCTION(AActor, A_SetSize)
 	PARAM_SELF_PROLOGUE(AActor);
 	PARAM_FLOAT(newradius);
 	PARAM_FLOAT_DEF(newheight);
+	PARAM_BOOL_DEF(testpos);
 
 	if (newradius < 0.)		newradius = self->radius;
 	if (newheight < 0.)		newheight = self->Height;
 
+	double oldradius = self->radius;
+	double oldheight = self->Height;
+
 	self->UnlinkFromWorld();
 	self->radius = newradius;
 	self->Height = newheight;
 	self->LinkToWorld();
-	return 0;
+
+	if (testpos && !P_TestMobjLocation(self))
+	{
+		self->UnlinkFromWorld();
+		self->radius = oldradius;
+		self->Height = oldheight;
+		self->LinkToWorld();
+		ACTION_RETURN_BOOL(false);
+	}
+
+	ACTION_RETURN_BOOL(true);
 }
diff --git a/wadsrc/static/zscript/actor.txt b/wadsrc/static/zscript/actor.txt
index 2a5d8c53d..0d264580a 100644
--- a/wadsrc/static/zscript/actor.txt
+++ b/wadsrc/static/zscript/actor.txt
@@ -793,7 +793,7 @@ class Actor : Thinker native
 	native bool A_CopySpriteFrame(int from, int to, int flags = 0);
 	native bool A_SetVisibleRotation(double anglestart = 0, double angleend = 0, double pitchstart = 0, double pitchend = 0, int flags = 0, int ptr = AAPTR_DEFAULT);
 	native void A_SetTranslation(name transname);
-	native void A_SetSize(double newradius, double newheight = -1);
+	native bool A_SetSize(double newradius, double newheight = -1, bool testpos = false);
 
 	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);