diff --git a/src/r_segs.cpp b/src/r_segs.cpp
index 8c22b3e53..e93ee4437 100644
--- a/src/r_segs.cpp
+++ b/src/r_segs.cpp
@@ -1951,16 +1951,31 @@ void R_NewWall (bool needlights)
 				rw_midtexturescalex = sidedef->GetTextureXScale(side_t::mid);
 				rw_midtexturescaley = sidedef->GetTextureYScale(side_t::mid);
 				yrepeat = FixedMul(midtexture->yScale, rw_midtexturescaley);
-				if (linedef->flags & ML_DONTPEGBOTTOM)
-				{ // bottom of texture at bottom
-					rw_midtexturemid = MulScale16(frontsector->GetPlaneTexZ(sector_t::floor) - viewz, yrepeat) + (midtexture->GetHeight() << FRACBITS);
+				if (yrepeat >= 0)
+				{ // normal orientation
+					if (linedef->flags & ML_DONTPEGBOTTOM)
+					{ // bottom of texture at bottom
+						rw_midtexturemid = MulScale16(frontsector->GetPlaneTexZ(sector_t::floor) - viewz, yrepeat) + (midtexture->GetHeight() << FRACBITS);
+					}
+					else
+					{ // top of texture at top
+						rw_midtexturemid = MulScale16(frontsector->GetPlaneTexZ(sector_t::ceiling) - viewz, yrepeat);
+						if (rowoffset < 0 && midtexture != NULL)
+						{
+							rowoffset += midtexture->GetHeight() << FRACBITS;
+						}
+					}
 				}
 				else
-				{ // top of texture at top
-					rw_midtexturemid = MulScale16(frontsector->GetPlaneTexZ(sector_t::ceiling) - viewz, yrepeat);
-					if (rowoffset < 0 && midtexture != NULL)
-					{
-						rowoffset += midtexture->GetHeight() << FRACBITS;
+				{ // upside down
+					rowoffset = -rowoffset;
+					if (linedef->flags & ML_DONTPEGBOTTOM)
+					{ // top of texture at bottom
+						rw_midtexturemid = MulScale16(frontsector->GetPlaneTexZ(sector_t::floor) - viewz, yrepeat);
+					}
+					else
+					{ // bottom of texture at top
+						rw_midtexturemid = MulScale16(frontsector->GetPlaneTexZ(sector_t::ceiling) - viewz, yrepeat) + (midtexture->GetHeight() << FRACBITS);
 					}
 				}
 				if (midtexture->bWorldPanning)
@@ -2096,17 +2111,32 @@ void R_NewWall (bool needlights)
 			rw_toptexturescalex = sidedef->GetTextureXScale(side_t::top);
 			rw_toptexturescaley = sidedef->GetTextureYScale(side_t::top);
 			yrepeat = FixedMul(toptexture->yScale, rw_toptexturescaley);
-			if (linedef->flags & ML_DONTPEGTOP)
-			{ // top of texture at top
-				rw_toptexturemid = MulScale16 (frontsector->GetPlaneTexZ(sector_t::ceiling) - viewz, yrepeat);
-				if (rowoffset < 0 && toptexture != NULL)
-				{
-					rowoffset += toptexture->GetHeight() << FRACBITS;
+			if (yrepeat >= 0)
+			{ // normal orientation
+				if (linedef->flags & ML_DONTPEGTOP)
+				{ // top of texture at top
+					rw_toptexturemid = MulScale16(frontsector->GetPlaneTexZ(sector_t::ceiling) - viewz, yrepeat);
+					if (rowoffset < 0 && toptexture != NULL)
+					{
+						rowoffset += toptexture->GetHeight() << FRACBITS;
+					}
+				}
+				else
+				{ // bottom of texture at bottom
+					rw_toptexturemid = MulScale16(backsector->GetPlaneTexZ(sector_t::ceiling) - viewz, yrepeat) + (toptexture->GetHeight() << FRACBITS);
 				}
 			}
 			else
-			{ // bottom of texture at bottom
-				rw_toptexturemid = MulScale16(backsector->GetPlaneTexZ(sector_t::ceiling) - viewz, yrepeat) + (toptexture->GetHeight() << FRACBITS);
+			{ // upside down
+				rowoffset = -rowoffset;
+				if (linedef->flags & ML_DONTPEGTOP)
+				{ // bottom of texture at top
+					rw_toptexturemid = MulScale16(frontsector->GetPlaneTexZ(sector_t::ceiling) - viewz, yrepeat) + (toptexture->GetHeight() << FRACBITS);
+				}
+				else
+				{ // top of texture at bottom
+					rw_toptexturemid = MulScale16(backsector->GetPlaneTexZ(sector_t::ceiling) - viewz, yrepeat);
+				}
 			}
 			if (toptexture->bWorldPanning)
 			{
@@ -2126,25 +2156,40 @@ void R_NewWall (bool needlights)
 			rw_bottomtexturescalex = sidedef->GetTextureXScale(side_t::bottom);
 			rw_bottomtexturescaley = sidedef->GetTextureYScale(side_t::bottom);
 			yrepeat = FixedMul(bottomtexture->yScale, rw_bottomtexturescaley);
-			if (linedef->flags & ML_DONTPEGBOTTOM)
-			{ // bottom of texture at bottom
-				rw_bottomtexturemid = rw_frontlowertop;
+			if (yrepeat >= 0)
+			{ // normal orientation
+				if (linedef->flags & ML_DONTPEGBOTTOM)
+				{ // bottom of texture at bottom
+					rw_bottomtexturemid = MulScale16(rw_frontlowertop - viewz, yrepeat);
+				}
+				else
+				{ // top of texture at top
+					rw_bottomtexturemid = MulScale16(backsector->GetPlaneTexZ(sector_t::floor) - viewz, yrepeat);
+					if (rowoffset < 0 && bottomtexture != NULL)
+					{
+						rowoffset += bottomtexture->GetHeight() << FRACBITS;
+					}
+				}
 			}
 			else
-			{ // top of texture at top
-				rw_bottomtexturemid = backsector->GetPlaneTexZ(sector_t::floor);
-				if (rowoffset < 0 && bottomtexture != NULL)
-				{
-					rowoffset += bottomtexture->GetHeight() << FRACBITS;
+			{ // upside down
+				rowoffset = -rowoffset;
+				if (linedef->flags & ML_DONTPEGBOTTOM)
+				{ // top of texture at bottom
+					rw_bottomtexturemid = MulScale16(rw_frontlowertop - viewz, yrepeat);
+				}
+				else
+				{ // bottom of texture at top
+					rw_bottomtexturemid = MulScale16(backsector->GetPlaneTexZ(sector_t::floor) - viewz, yrepeat) + (bottomtexture->GetHeight() << FRACBITS);
 				}
 			}
 			if (bottomtexture->bWorldPanning)
 			{
-				rw_bottomtexturemid = MulScale16(rw_bottomtexturemid - viewz + rowoffset, yrepeat);
+				rw_bottomtexturemid += MulScale16(rowoffset, yrepeat);
 			}
 			else
 			{
-				rw_bottomtexturemid = MulScale16(rw_bottomtexturemid - viewz, yrepeat) + rowoffset;
+				rw_bottomtexturemid += rowoffset;
 			}
 		}
 	}