diff --git a/docs/rh-log.txt b/docs/rh-log.txt
index b6b6cf588..2cd47564c 100644
--- a/docs/rh-log.txt
+++ b/docs/rh-log.txt
@@ -1,4 +1,5 @@
 May 17, 2008 (Changes by Graf Zahl)
+- Fixed coordinate checks for objects on 3DMidtex lines.
 - Fixed: All translucent blending operations for CopyColors must treat an 
   alpha of 0 so that the pixel is not modified or texture composition as 
   intended will not work.
diff --git a/src/p_map.cpp b/src/p_map.cpp
index 88eb13a14..c4ac9d5f3 100644
--- a/src/p_map.cpp
+++ b/src/p_map.cpp
@@ -150,6 +150,10 @@ static bool PIT_FindFloorCeiling (line_t *ld, const FBoundingBox &box, FCheckPos
 		tmf.floorsector = open.bottomsec;
 		tmf.touchmidtex = open.touchmidtex;
 	}
+	else if (open.bottom == tmf.floorz)
+	{
+		tmf.touchmidtex |= open.touchmidtex;
+	}
 
 	if (open.lowfloor < tmf.dropoffz)
 		tmf.dropoffz = open.lowfloor;
@@ -194,7 +198,7 @@ void P_FindFloorCeiling (AActor *actor, bool onlymidtex)
 
 	if (tmf.touchmidtex) tmf.dropoffz = tmf.floorz;
 
-	if (!onlymidtex || (tmf.touchmidtex && (tmf.floorz < actor->z)))
+	if (!onlymidtex || (tmf.touchmidtex && (tmf.floorz <= actor->z)))
 	{
 		actor->floorz = tmf.floorz;
 		actor->dropoffz = tmf.dropoffz;
@@ -629,6 +633,10 @@ bool PIT_CheckLine (line_t *ld, const FBoundingBox &box, FCheckPosition &tm)
 		tm.touchmidtex = open.touchmidtex;
 		tm.thing->BlockingLine = ld;
 	}
+	else if (open.bottom == tm.floorz)
+	{
+		tm.touchmidtex |= open.touchmidtex;
+	}
 
 	if (open.lowfloor < tm.dropoffz)
 		tm.dropoffz = open.lowfloor;
@@ -1133,7 +1141,11 @@ bool P_CheckPosition (AActor *thing, fixed_t x, fixed_t y, FCheckPosition &tm)
 	if (tm.ceilingz - tm.floorz < thing->height)
 		return false;
 
-	if (tm.stepthing != NULL || tm.touchmidtex)
+	if (tm.touchmidtex)
+	{
+		tm.dropoffz = tm.floorz;
+	}
+	else if (tm.stepthing != NULL)
 	{
 		tm.dropoffz = thingdropoffz;
 	}
diff --git a/src/p_mobj.cpp b/src/p_mobj.cpp
index 08f1a5f62..d4b172d91 100644
--- a/src/p_mobj.cpp
+++ b/src/p_mobj.cpp
@@ -1758,7 +1758,12 @@ explode:
 			|| mo->momy > FRACUNIT/4 || mo->momy < -FRACUNIT/4)
 		{
 			if (mo->floorz > mo->Sector->floorplane.ZatPoint (mo->x, mo->y))
-				return;
+			{
+				if (mo->dropoffz != mo->floorz) // 3DMidtex or other special cases that must be excluded
+				{
+					return;
+				}
+			}
 		}
 	}
 
@@ -4029,6 +4034,7 @@ AActor *P_SpawnMapThing (FMapThing *mthing, int position)
 	mobj->SpawnPoint[2] = mthing->z;
 	mobj->SpawnAngle = mthing->angle;
 	mobj->SpawnFlags = mthing->flags;
+	P_FindFloorCeiling(mobj, true);
 
 	if (!(mobj->flags2 & MF2_ARGSDEFINED))
 	{