diff --git a/src/p_mobj.c b/src/p_mobj.c
index 2a1c5d97f..fcba1f690 100644
--- a/src/p_mobj.c
+++ b/src/p_mobj.c
@@ -11614,7 +11614,7 @@ void P_MovePlayerToStarpost(INT32 playernum)
 mapthing_t *huntemeralds[MAXHUNTEMERALDS];
 INT32 numhuntemeralds;
 
-fixed_t P_GetMobjSpawnHeight(const mobjtype_t mobjtype, const fixed_t x, const fixed_t y, const fixed_t offset, const boolean flip, const fixed_t scale)
+fixed_t P_GetMobjSpawnHeight(const mobjtype_t mobjtype, const fixed_t x, const fixed_t y, const fixed_t dz, const fixed_t offset, const boolean flip, const fixed_t scale)
 {
 	const subsector_t *ss = R_PointInSubsector(x, y);
 
@@ -11624,14 +11624,15 @@ fixed_t P_GetMobjSpawnHeight(const mobjtype_t mobjtype, const fixed_t x, const f
 
 	// Establish height.
 	if (flip)
-		return P_GetSectorCeilingZAt(ss->sector, x, y) - FixedMul(scale, offset + mobjinfo[mobjtype].height);
+		return P_GetSectorCeilingZAt(ss->sector, x, y) - dz - FixedMul(scale, offset + mobjinfo[mobjtype].height);
 	else
-		return P_GetSectorFloorZAt(ss->sector, x, y) + FixedMul(scale, offset);
+		return P_GetSectorFloorZAt(ss->sector, x, y) + dz + FixedMul(scale, offset);
 }
 
 fixed_t P_GetMapThingSpawnHeight(const mobjtype_t mobjtype, const mapthing_t* mthing, const fixed_t x, const fixed_t y)
 {
-	fixed_t offset = mthing->z << FRACBITS;
+	fixed_t dz = mthing->z << FRACBITS; // Base offset from the floor.
+	fixed_t offset = 0; // Specific scaling object offset.
 	boolean flip = (!!(mobjinfo[mobjtype].flags & MF_SPAWNCEILING) ^ !!(mthing->options & MTF_OBJECTFLIP));
 
 	switch (mobjtype)
@@ -11647,17 +11648,17 @@ fixed_t P_GetMapThingSpawnHeight(const mobjtype_t mobjtype, const mapthing_t* mt
 	case MT_JETTBOMBER:
 	case MT_JETTGUNNER:
 	case MT_EGGMOBILE2:
-		if (!offset)
-			offset = 33*FRACUNIT;
+		if (!dz)
+			dz = 33*FRACUNIT;
 		break;
 	case MT_EGGMOBILE:
-		if (!offset)
-			offset = 128*FRACUNIT;
+		if (!dz)
+			dz = 128*FRACUNIT;
 		break;
 	case MT_GOLDBUZZ:
 	case MT_REDBUZZ:
-		if (!offset)
-			offset = 288*FRACUNIT;
+		if (!dz)
+			dz = 288*FRACUNIT;
 		break;
 
 	// Horizontal springs, may float additional units with MTF_AMBUSH.
@@ -11690,7 +11691,7 @@ fixed_t P_GetMapThingSpawnHeight(const mobjtype_t mobjtype, const mapthing_t* mt
 			offset += mthing->options & MTF_AMBUSH ? 24*FRACUNIT : 0;
 	}
 
-	if (!offset) // Snap to the surfaces when there's no offset set.
+	if (!(dz + offset)) // Snap to the surfaces when there's no offset set.
 	{
 		if (flip)
 			return ONCEILINGZ;
@@ -11698,7 +11699,7 @@ fixed_t P_GetMapThingSpawnHeight(const mobjtype_t mobjtype, const mapthing_t* mt
 			return ONFLOORZ;
 	}
 
-	return P_GetMobjSpawnHeight(mobjtype, x, y, offset, flip, mthing->scale);
+	return P_GetMobjSpawnHeight(mobjtype, x, y, dz, offset, flip, mthing->scale);
 }
 
 static boolean P_SpawnNonMobjMapThing(mapthing_t *mthing)
@@ -13187,7 +13188,7 @@ static void P_SpawnHoopInternal(mapthing_t *mthing, INT32 hoopsize, fixed_t size
 	TVector v, *res;
 	fixed_t x = mthing->x << FRACBITS;
 	fixed_t y = mthing->y << FRACBITS;
-	fixed_t z = P_GetMobjSpawnHeight(MT_HOOP, x, y, mthing->z << FRACBITS, false, mthing->scale);
+	fixed_t z = P_GetMobjSpawnHeight(MT_HOOP, x, y, mthing->z << FRACBITS, 0, false, mthing->scale);
 
 	hoopcenter = P_SpawnMobj(x, y, z, MT_HOOPCENTER);
 	hoopcenter->spawnpoint = mthing;
@@ -13332,7 +13333,7 @@ static void P_SpawnItemRow(mapthing_t *mthing, mobjtype_t* itemtypes, UINT8 numi
 			itemtypes[r] = P_GetMobjtypeSubstitute(&dummything, itemtypes[r]);
 		}
 	}
-	z = P_GetMobjSpawnHeight(itemtypes[0], x, y, z, mthing->options & MTF_OBJECTFLIP, mthing->scale);
+	z = P_GetMobjSpawnHeight(itemtypes[0], x, y, z, 0, mthing->options & MTF_OBJECTFLIP, mthing->scale);
 
 	for (r = 0; r < numitems; r++)
 	{
@@ -13390,7 +13391,7 @@ static void P_SpawnItemCircle(mapthing_t *mthing, mobjtype_t *itemtypes, UINT8 n
 			itemtypes[i] = P_GetMobjtypeSubstitute(&dummything, itemtypes[i]);
 		}
 	}
-	z = P_GetMobjSpawnHeight(itemtypes[0], x, y, z, false, mthing->scale);
+	z = P_GetMobjSpawnHeight(itemtypes[0], x, y, z, 0, false, mthing->scale);
 
 	for (i = 0; i < numitems; i++)
 	{
diff --git a/src/p_mobj.h b/src/p_mobj.h
index 92f354215..27a6ef4f0 100644
--- a/src/p_mobj.h
+++ b/src/p_mobj.h
@@ -452,7 +452,7 @@ void P_MovePlayerToSpawn(INT32 playernum, mapthing_t *mthing);
 void P_MovePlayerToStarpost(INT32 playernum);
 void P_AfterPlayerSpawn(INT32 playernum);
 
-fixed_t P_GetMobjSpawnHeight(const mobjtype_t mobjtype, const fixed_t x, const fixed_t y, const fixed_t offset, const boolean flip, const fixed_t scale);
+fixed_t P_GetMobjSpawnHeight(const mobjtype_t mobjtype, const fixed_t x, const fixed_t y, const fixed_t dz, const fixed_t offset, const boolean flip, const fixed_t scale);
 fixed_t P_GetMapThingSpawnHeight(const mobjtype_t mobjtype, const mapthing_t* mthing, const fixed_t x, const fixed_t y);
 
 mobj_t *P_SpawnMapThing(mapthing_t *mthing);