diff --git a/src/r_main.cpp b/src/r_main.cpp
index 5af77e97d7..2b9a3e9a1e 100644
--- a/src/r_main.cpp
+++ b/src/r_main.cpp
@@ -160,6 +160,7 @@ fixed_t			globaluclip, globaldclip;
 fixed_t 		centerxfrac;
 fixed_t 		centeryfrac;
 fixed_t			yaspectmul;
+fixed_t			baseyaspectmul;		// yaspectmul without a forced aspect ratio
 float			iyaspectmulfloat;
 fixed_t			InvZtoScale;
 
@@ -604,7 +605,7 @@ void R_SetViewSize (int blocks)
 
 void R_SetWindow (int windowSize, int fullWidth, int fullHeight, int stHeight)
 {
-	int virtheight, virtwidth;
+	int virtheight, virtwidth, trueratio, virtwidth2, virtheight2;
 
 	if (windowSize >= 11)
 	{
@@ -625,7 +626,7 @@ void R_SetWindow (int windowSize, int fullWidth, int fullHeight, int stHeight)
 	}
 
 	// If the screen is approximately 16:9 or 16:10, consider it widescreen.
-	WidescreenRatio = CheckRatio (fullWidth, fullHeight);
+	WidescreenRatio = CheckRatio (fullWidth, fullHeight, &trueratio);
 
 	DrawFSHUD = (windowSize == 11);
 	
@@ -648,8 +649,18 @@ void R_SetWindow (int windowSize, int fullWidth, int fullHeight, int stHeight)
 	centerxfrac = centerx<<FRACBITS;
 	centeryfrac = centery<<FRACBITS;
 
-	virtwidth = fullWidth;
-	virtheight = fullHeight;
+	virtwidth = virtwidth2 = fullWidth;
+	virtheight = virtheight2 = fullHeight;
+
+	if (trueratio & 4)
+	{
+		virtheight2 = virtheight2 * BaseRatioSizes[trueratio][3] / 48;
+	}
+	else
+	{
+		virtwidth2 = virtwidth2 * BaseRatioSizes[trueratio][3] / 48;
+	}
+
 	if (WidescreenRatio & 4)
 	{
 		virtheight = virtheight * BaseRatioSizes[WidescreenRatio][3] / 48;
@@ -661,6 +672,7 @@ void R_SetWindow (int windowSize, int fullWidth, int fullHeight, int stHeight)
 		centerxwide = centerx * BaseRatioSizes[WidescreenRatio][3] / 48;
 	}
 
+	baseyaspectmul = Scale(320 << FRACBITS, virtheight2, r_Yaspect * virtwidth2);
 	yaspectmul = Scale ((320<<FRACBITS), virtheight, r_Yaspect * virtwidth);
 	iyaspectmulfloat = (float)virtwidth * r_Yaspect / 320.f / (float)virtheight;
 	InvZtoScale = yaspectmul * centerx;
diff --git a/src/r_things.cpp b/src/r_things.cpp
index 1bc81ce4c0..0181f7d758 100644
--- a/src/r_things.cpp
+++ b/src/r_things.cpp
@@ -3244,6 +3244,8 @@ static fixed_t distrecip(fixed_t y)
 	return y == 0 ? 0 : SafeDivScale32(centerxwide, y);
 }
 
+extern fixed_t baseyaspectmul;
+
 void R_DrawVoxel(fixed_t dasprx, fixed_t daspry, fixed_t dasprz, angle_t dasprang,
 	fixed_t daxscale, fixed_t dayscale, FVoxel *voxobj,
 	lighttable_t *colormap, short *daumost, short *dadmost, int minslabz, int maxslabz, int flags)
@@ -3293,7 +3295,7 @@ void R_DrawVoxel(fixed_t dasprx, fixed_t daspry, fixed_t dasprz, angle_t daspran
 	maxslabz >>= k;
 
 	daxscale <<= (k+8); dayscale <<= (k+8);
-	dazscale = FixedDiv(dayscale, yaspectmul);
+	dazscale = FixedDiv(dayscale, baseyaspectmul);
 	daxscale = FixedDiv(daxscale, yaspectmul);
 	daxscale = Scale(daxscale, xdimenscale, centerxwide << 9);
 	dayscale = Scale(dayscale, FixedMul(xdimenscale, viewingrangerecip), centerxwide << 9);
diff --git a/src/v_video.cpp b/src/v_video.cpp
index c2709c62fe..8de9e0de94 100644
--- a/src/v_video.cpp
+++ b/src/v_video.cpp
@@ -1739,43 +1739,61 @@ CUSTOM_CVAR (Int, vid_aspect, 0, CVAR_GLOBALCONFIG|CVAR_ARCHIVE)
 // 1: 16:9
 // 2: 16:10
 // 4: 5:4
-int CheckRatio (int width, int height)
+int CheckRatio (int width, int height, int *trueratio)
 {
+	int fakeratio = -1;
+	int ratio;
+
 	if ((vid_aspect >=1) && (vid_aspect <=4))
 	{
 		// [SP] User wants to force aspect ratio; let them.
-		return vid_aspect == 3? 0: int(vid_aspect);
+		fakeratio = vid_aspect == 3? 0: int(vid_aspect);
 	}
 	if (vid_nowidescreen)
 	{
 		if (!vid_tft)
 		{
-			return 0;
+			fakeratio = 0;
+		}
+		else
+		{
+			fakeratio = (height * 5/4 == width) ? 4 : 0;
 		}
-		return (height * 5/4 == width) ? 4 : 0;
 	}
 	// If the size is approximately 16:9, consider it so.
 	if (abs (height * 16/9 - width) < 10)
 	{
-		return 1;
+		ratio = 1;
 	}
 	// 16:10 has more variance in the pixel dimensions. Grr.
-	if (abs (height * 16/10 - width) < 60)
+	else if (abs (height * 16/10 - width) < 60)
 	{
 		// 320x200 and 640x400 are always 4:3, not 16:10
 		if ((width == 320 && height == 200) || (width == 640 && height == 400))
 		{
-			return 0;
+			ratio = 0;
+		}
+		else
+		{
+			ratio = 2;
 		}
-		return 2;
 	}
 	// Unless vid_tft is set, 1280x1024 is 4:3, not 5:4.
-	if (height * 5/4 == width && vid_tft)
+	else if (height * 5/4 == width && vid_tft)
 	{
-		return 4;
+		ratio = 4;
 	}
 	// Assume anything else is 4:3.
-	return 0;
+	else
+	{
+		ratio = 0;
+	}
+
+	if (trueratio != NULL)
+	{
+		*trueratio = ratio;
+	}
+	return (fakeratio >= 0) ? fakeratio : ratio;
 }
 
 // First column: Base width (unused)
diff --git a/src/v_video.h b/src/v_video.h
index 684b5e36a1..399d644809 100644
--- a/src/v_video.h
+++ b/src/v_video.h
@@ -500,7 +500,7 @@ void V_DrawFrame (int left, int top, int width, int height);
 extern "C" void ASM_PatchPitch (void);
 #endif
 
-int CheckRatio (int width, int height);
+int CheckRatio (int width, int height, int *trueratio=NULL);
 static inline int CheckRatio (double width, double height) { return CheckRatio(int(width), int(height)); }
 extern const int BaseRatioSizes[5][4];