diff --git a/src/r_plane.cpp b/src/r_plane.cpp
index c4d72b1a09..0d87be4b9b 100644
--- a/src/r_plane.cpp
+++ b/src/r_plane.cpp
@@ -1404,7 +1404,7 @@ void R_DrawPortals ()
 		vissprite_p = firstvissprite;
 
 		visplaneStack.Pop (pl);
-		if (pl->Alpha > 0)
+		if (pl->Alpha > 0 && pl->picnum != skyflatnum)
 		{
 			R_DrawSinglePlane (pl, pl->Alpha, pl->Additive, true);
 		}