diff --git a/src/r_bsp.c b/src/r_bsp.c
index 34b082ca..d47c1140 100644
--- a/src/r_bsp.c
+++ b/src/r_bsp.c
@@ -222,30 +222,6 @@ void R_PortalClearClipSegs(INT32 start, INT32 end)
 	newend = solidsegs + 2;
 }
 
-
-// R_DoorClosed
-//
-// This function is used to fix the automap bug which
-// showed lines behind closed doors simply because the door had a dropoff.
-//
-// It assumes that Doom has already ruled out a door being closed because
-// of front-back closure (e.g. front floor is taller than back ceiling).
-static INT32 R_DoorClosed(void)
-{
-	return
-
-	// if door is closed because back is shut:
-	backsector->ceilingheight <= backsector->floorheight
-
-	// preserve a kind of transparent door/lift special effect:
-	&& (backsector->ceilingheight >= frontsector->ceilingheight || curline->sidedef->toptexture)
-
-	&& (backsector->floorheight <= frontsector->floorheight || curline->sidedef->bottomtexture)
-
-	// properly render skies (consider door "open" if both ceilings are sky):
-	&& (backsector->ceilingpic != skyflatnum || frontsector->ceilingpic != skyflatnum);
-}
-
 //
 // If player's view height is underneath fake floor, lower the
 // drawn ceiling to be just under the floor height, and replace
@@ -534,7 +510,11 @@ static void R_AddLine(seg_t *line)
 		}
 
 		// Check for automap fix. Store in doorclosed for r_segs.c
-		doorclosed = R_DoorClosed();
+		doorclosed = (backsector->ceilingheight <= backsector->floorheight
+		&& (backsector->ceilingheight >= frontsector->ceilingheight || curline->sidedef->toptexture)
+		&& (backsector->floorheight <= frontsector->floorheight || curline->sidedef->bottomtexture)
+		&& (backsector->ceilingpic != skyflatnum || frontsector->ceilingpic != skyflatnum));
+
 		if (doorclosed)
 			goto clipsolid;