diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index 4394339573..998f49231c 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,4 +1,6 @@
 August 11, 2006 (Changes by Graf Zahl)
+- Fixed: P_CheckOnMobjZ returned the first thing an actor could stand on, 
+  not the highest possible.
 - Added disintegration damage to SectorDamage.
 - Bumped savegame version, min. savegame version, netgame version and
   demo version because the inventory and damage changes are incompatible
diff --git a/src/p_local.h b/src/p_local.h
index eab98d1440..22b1aeb7ef 100644
--- a/src/p_local.h
+++ b/src/p_local.h
@@ -277,7 +277,7 @@ extern bool				DoRipping;
 extern AActor			*LastRipped;
 
 BOOL	P_TestMobjLocation (AActor *mobj);
-bool	P_TestMobjZ (AActor *mobj);
+bool	P_TestMobjZ (AActor *mobj, bool quick=true);
 BOOL	P_CheckPosition (AActor *thing, fixed_t x, fixed_t y);
 AActor	*P_CheckOnmobj (AActor *thing);
 void	P_FakeZMovement (AActor *mo);
diff --git a/src/p_map.cpp b/src/p_map.cpp
index cf65de0dcd..c75f927cfd 100644
--- a/src/p_map.cpp
+++ b/src/p_map.cpp
@@ -1171,13 +1171,17 @@ BOOL PIT_CheckOnmobjZ (AActor *thing)
 	{ // under thing
 		return true;
 	}
+	else if (!tmflags && onmobj != NULL && thing->z + thing->height < onmobj->z + onmobj->height)
+	{ // something higher is in the way
+		return true;
+	}
 	fixed_t blockdist = thing->radius+tmthing->radius;
 	if (abs(thing->x-tmx) >= blockdist || abs(thing->y-tmy) >= blockdist)
 	{ // Didn't hit thing
 		return true;
 	}
 	onmobj = thing;
-	return false;
+	return !tmflags;
 }
 
 /*
@@ -1421,7 +1425,7 @@ AActor *P_CheckOnmobj (AActor *thing)
 
 	oldz = thing->z;
 	P_FakeZMovement (thing);
-	good = P_TestMobjZ (thing);
+	good = P_TestMobjZ (thing, false);
 	thing->z = oldz;
 
 	return good ? NULL : onmobj;
@@ -1433,19 +1437,21 @@ AActor *P_CheckOnmobj (AActor *thing)
 //
 //=============================================================================
 
-bool P_TestMobjZ (AActor *actor)
+bool P_TestMobjZ (AActor *actor, bool quick)
 {
 	static TArray<AActor *> mobjzbt;
 
 	int	xl,xh,yl,yh,bx,by;
 	fixed_t x, y;
 
+	onmobj = NULL;
 	if (actor->flags & MF_NOCLIP)
 		return true;
 
 	tmx = x = actor->x;
 	tmy = y = actor->y;
 	tmthing = actor;
+	tmflags = quick;
 
 	tmbbox[BOXTOP] = y + actor->radius;
 	tmbbox[BOXBOTTOM] = y - actor->radius;
@@ -1468,7 +1474,7 @@ bool P_TestMobjZ (AActor *actor)
 			if (!P_BlockThingsIterator (bx, by, PIT_CheckOnmobjZ, mobjzbt))
 				return false;
 
-	return true;
+	return onmobj == NULL;
 }
 
 //=============================================================================