diff --git a/src/swrenderer/line/r_wallsetup.cpp b/src/swrenderer/line/r_wallsetup.cpp
index 071ae799d..579ff21f2 100644
--- a/src/swrenderer/line/r_wallsetup.cpp
+++ b/src/swrenderer/line/r_wallsetup.cpp
@@ -159,19 +159,35 @@ namespace swrenderer
 		float invZ = WallT.InvZorg + WallT.InvZstep * (float)(x1 + 0.5 - viewport->CenterX);
 		float uGradient = WallT.UoverZstep;
 		float zGradient = WallT.InvZstep;
-		float xrepeat = (float)walxrepeat;
+		float xrepeat = (float)fabs(walxrepeat);
 		float depthScale = (float)(WallT.InvZstep * viewport->WallTMapScale2);
 		float depthOrg = (float)(-WallT.UoverZstep * viewport->WallTMapScale2);
 
-		for (int x = x1; x < x2; x++)
+		if (walxrepeat < 0.0)
 		{
-			float u = uOverZ / invZ;
+			for (int x = x1; x < x2; x++)
+			{
+				float u = uOverZ / invZ;
 
-			UPos[x] = (fixed_t)(u * xrepeat * FRACUNIT);
-			VStep[x] = depthOrg + u * depthScale;
+				UPos[x] = (fixed_t)((xrepeat - u * xrepeat) * FRACUNIT);
+				VStep[x] = depthOrg + u * depthScale;
 
-			uOverZ += uGradient;
-			invZ += zGradient;
+				uOverZ += uGradient;
+				invZ += zGradient;
+			}
+		}
+		else
+		{
+			for (int x = x1; x < x2; x++)
+			{
+				float u = uOverZ / invZ;
+
+				UPos[x] = (fixed_t)(u * xrepeat * FRACUNIT);
+				VStep[x] = depthOrg + u * depthScale;
+
+				uOverZ += uGradient;
+				invZ += zGradient;
+			}
 		}
 	}
 
@@ -183,16 +199,31 @@ namespace swrenderer
 		float invZ = WallT.InvZorg + WallT.InvZstep * (float)(x1 + 0.5 - viewport->CenterX);
 		float uGradient = WallT.UoverZstep;
 		float zGradient = WallT.InvZstep;
-		float xrepeat = (float)walxrepeat;
+		float xrepeat = (float)fabs(walxrepeat);
 
-		for (int x = x1; x < x2; x++)
+		if (walxrepeat < 0.0f)
 		{
-			float u = uOverZ / invZ * xrepeat;
+			for (int x = x1; x < x2; x++)
+			{
+				float u = uOverZ / invZ * xrepeat - xrepeat;
 
-			UPos[x] = (fixed_t)(u * FRACUNIT);
+				UPos[x] = (fixed_t)(u * FRACUNIT);
 
-			uOverZ += uGradient;
-			invZ += zGradient;
+				uOverZ += uGradient;
+				invZ += zGradient;
+			}
+		}
+		else
+		{
+			for (int x = x1; x < x2; x++)
+			{
+				float u = uOverZ / invZ * xrepeat;
+
+				UPos[x] = (fixed_t)(u * FRACUNIT);
+
+				uOverZ += uGradient;
+				invZ += zGradient;
+			}
 		}
 	}
 }