diff --git a/src/r_plane.cpp b/src/r_plane.cpp
index 1a7758923..581e8b732 100644
--- a/src/r_plane.cpp
+++ b/src/r_plane.cpp
@@ -1529,7 +1529,7 @@ void R_DrawNormalPlane (visplane_t *pl, double _xscale, double _yscale, fixed_t
 				{
 					spanfunc = R_DrawSpanAddClamp;
 					dc_srcalpha = alpha;
-					dc_destalpha = OPAQUE-alpha;
+					dc_destalpha = FRACUNIT;
 				}
 			}
 			else