diff --git a/src/r_draw8.c b/src/r_draw8.c
index 015dac2a7..2f6bdcfa4 100644
--- a/src/r_draw8.c
+++ b/src/r_draw8.c
@@ -644,6 +644,7 @@ void R_CalcTiltedLighting(fixed_t start, fixed_t end)
 	}
 }
 
+#define PLANELIGHTFLOAT (BASEVIDWIDTH * BASEVIDWIDTH / vid.width / (zeroheight - FIXED_TO_FLOAT(viewz)) / 21.0f * FIXED_TO_FLOAT(fovtan))
 
 /**	\brief The R_DrawTiltedSpan_8 function
 	Draw slopes! Holy sheit!
@@ -669,7 +670,7 @@ void R_DrawTiltedSpan_8(void)
 
 	// Lighting is simple. It's just linear interpolation from start to end
 	{
-		float planelightfloat = BASEVIDWIDTH*BASEVIDWIDTH/vid.width / (zeroheight - FIXED_TO_FLOAT(viewz)) / 21.0f;
+		float planelightfloat = PLANELIGHTFLOAT;
 		float lightstart, lightend;
 
 		lightend = (iz + ds_szp->x*width) * planelightfloat;
@@ -805,7 +806,7 @@ void R_DrawTiltedTranslucentSpan_8(void)
 
 	// Lighting is simple. It's just linear interpolation from start to end
 	{
-		float planelightfloat = BASEVIDWIDTH*BASEVIDWIDTH/vid.width / (zeroheight - FIXED_TO_FLOAT(viewz)) / 21.0f;
+		float planelightfloat = PLANELIGHTFLOAT;
 		float lightstart, lightend;
 
 		lightend = (iz + ds_szp->x*width) * planelightfloat;
@@ -942,7 +943,7 @@ void R_DrawTiltedTranslucentWaterSpan_8(void)
 
 	// Lighting is simple. It's just linear interpolation from start to end
 	{
-		float planelightfloat = BASEVIDWIDTH*BASEVIDWIDTH/vid.width / (zeroheight - FIXED_TO_FLOAT(viewz)) / 21.0f;
+		float planelightfloat = PLANELIGHTFLOAT;
 		float lightstart, lightend;
 
 		lightend = (iz + ds_szp->x*width) * planelightfloat;
@@ -1078,7 +1079,7 @@ void R_DrawTiltedSplat_8(void)
 
 	// Lighting is simple. It's just linear interpolation from start to end
 	{
-		float planelightfloat = BASEVIDWIDTH*BASEVIDWIDTH/vid.width / (zeroheight - FIXED_TO_FLOAT(viewz)) / 21.0f;
+		float planelightfloat = PLANELIGHTFLOAT;
 		float lightstart, lightend;
 
 		lightend = (iz + ds_szp->x*width) * planelightfloat;
diff --git a/src/r_draw8_npo2.c b/src/r_draw8_npo2.c
index 748ca195c..aa38ee2d9 100644
--- a/src/r_draw8_npo2.c
+++ b/src/r_draw8_npo2.c
@@ -62,6 +62,9 @@ void R_DrawSpan_NPO2_8 (void)
 }
 
 #ifdef ESLOPE
+
+#define PLANELIGHTFLOAT (BASEVIDWIDTH * BASEVIDWIDTH / vid.width / (zeroheight - FIXED_TO_FLOAT(viewz)) / 21.0f * FIXED_TO_FLOAT(fovtan))
+
 /**	\brief The R_DrawTiltedSpan_NPO2_8 function
 	Draw slopes! Holy sheit!
 */
@@ -86,7 +89,7 @@ void R_DrawTiltedSpan_NPO2_8(void)
 
 	// Lighting is simple. It's just linear interpolation from start to end
 	{
-		float planelightfloat = BASEVIDWIDTH*BASEVIDWIDTH/vid.width / (zeroheight - FIXED_TO_FLOAT(viewz)) / 21.0f;
+		float planelightfloat = PLANELIGHTFLOAT;
 		float lightstart, lightend;
 
 		lightend = (iz + ds_szp->x*width) * planelightfloat;
@@ -282,7 +285,7 @@ void R_DrawTiltedTranslucentSpan_NPO2_8(void)
 
 	// Lighting is simple. It's just linear interpolation from start to end
 	{
-		float planelightfloat = BASEVIDWIDTH*BASEVIDWIDTH/vid.width / (zeroheight - FIXED_TO_FLOAT(viewz)) / 21.0f;
+		float planelightfloat = PLANELIGHTFLOAT;
 		float lightstart, lightend;
 
 		lightend = (iz + ds_szp->x*width) * planelightfloat;
@@ -476,7 +479,7 @@ void R_DrawTiltedSplat_NPO2_8(void)
 
 	// Lighting is simple. It's just linear interpolation from start to end
 	{
-		float planelightfloat = BASEVIDWIDTH*BASEVIDWIDTH/vid.width / (zeroheight - FIXED_TO_FLOAT(viewz)) / 21.0f;
+		float planelightfloat = PLANELIGHTFLOAT;
 		float lightstart, lightend;
 
 		lightend = (iz + ds_szp->x*width) * planelightfloat;
@@ -869,7 +872,7 @@ void R_DrawTiltedTranslucentWaterSpan_NPO2_8(void)
 
 	// Lighting is simple. It's just linear interpolation from start to end
 	{
-		float planelightfloat = BASEVIDWIDTH*BASEVIDWIDTH/vid.width / (zeroheight - FIXED_TO_FLOAT(viewz)) / 21.0f;
+		float planelightfloat = PLANELIGHTFLOAT;
 		float lightstart, lightend;
 
 		lightend = (iz + ds_szp->x*width) * planelightfloat;
diff --git a/src/r_main.h b/src/r_main.h
index 0042015f2..678d3a0a7 100644
--- a/src/r_main.h
+++ b/src/r_main.h
@@ -46,6 +46,8 @@ extern size_t validcount, linecount, loopcount, framecount;
 #define MAXLIGHTZ 128
 #define LIGHTZSHIFT 20
 
+#define LIGHTRESOLUTIONFIX (640*fovtan/vid.width)
+
 extern lighttable_t *scalelight[LIGHTLEVELS][MAXLIGHTSCALE];
 extern lighttable_t *scalelightfixed[MAXLIGHTSCALE];
 extern lighttable_t *zlight[LIGHTLEVELS][MAXLIGHTZ];
diff --git a/src/r_segs.c b/src/r_segs.c
index dcb5fc160..fb4238448 100644
--- a/src/r_segs.c
+++ b/src/r_segs.c
@@ -199,7 +199,7 @@ static void R_DrawWallSplats(void)
 		// draw the columns
 		for (dc_x = x1; dc_x <= x2; dc_x++, spryscale += rw_scalestep)
 		{
-			pindex = FixedMul(spryscale, FixedDiv(640, vid.width))>>LIGHTSCALESHIFT;
+			pindex = FixedMul(spryscale, LIGHTRESOLUTIONFIX)>>LIGHTSCALESHIFT;
 			if (pindex >= MAXLIGHTSCALE)
 				pindex = MAXLIGHTSCALE - 1;
 			dc_colormap = walllights[pindex];
@@ -599,7 +599,7 @@ void R_RenderMaskedSegRange(drawseg_t *ds, INT32 x1, INT32 x2)
 						else
 							xwalllights = scalelight[rlight->lightnum];
 
-						pindex = FixedMul(spryscale, FixedDiv(640, vid.width))>>LIGHTSCALESHIFT;
+						pindex = FixedMul(spryscale, LIGHTRESOLUTIONFIX)>>LIGHTSCALESHIFT;
 
 						if (pindex >= MAXLIGHTSCALE)
 							pindex = MAXLIGHTSCALE - 1;
@@ -644,7 +644,7 @@ void R_RenderMaskedSegRange(drawseg_t *ds, INT32 x1, INT32 x2)
 				}
 
 				// calculate lighting
-				pindex = FixedMul(spryscale, FixedDiv(640, vid.width))>>LIGHTSCALESHIFT;
+				pindex = FixedMul(spryscale, LIGHTRESOLUTIONFIX)>>LIGHTSCALESHIFT;
 
 				if (pindex >= MAXLIGHTSCALE)
 					pindex = MAXLIGHTSCALE - 1;
@@ -1188,7 +1188,7 @@ void R_RenderThickSideRange(drawseg_t *ds, INT32 x1, INT32 x2, ffloor_t *pfloor)
 						else
 							xwalllights = scalelight[lightnum];
 
-						pindex = FixedMul(spryscale, FixedDiv(640, vid.width))>>LIGHTSCALESHIFT;
+						pindex = FixedMul(spryscale, LIGHTRESOLUTIONFIX)>>LIGHTSCALESHIFT;
 
 						if (pindex >= MAXLIGHTSCALE)
 							pindex = MAXLIGHTSCALE-1;
@@ -1281,7 +1281,7 @@ void R_RenderThickSideRange(drawseg_t *ds, INT32 x1, INT32 x2, ffloor_t *pfloor)
 			}
 
 			// calculate lighting
-			pindex = FixedMul(spryscale, FixedDiv(640, vid.width))>>LIGHTSCALESHIFT;
+			pindex = FixedMul(spryscale, LIGHTRESOLUTIONFIX)>>LIGHTSCALESHIFT;
 
 			if (pindex >= MAXLIGHTSCALE)
 				pindex = MAXLIGHTSCALE - 1;
@@ -1486,7 +1486,7 @@ static void R_RenderSegLoop (void)
 		if (segtextured)
 		{
 			// calculate lighting
-			pindex = FixedMul(rw_scale, FixedDiv(640, vid.width))>>LIGHTSCALESHIFT;
+			pindex = FixedMul(rw_scale, LIGHTRESOLUTIONFIX)>>LIGHTSCALESHIFT;
 
 			if (pindex >=  MAXLIGHTSCALE)
 				pindex = MAXLIGHTSCALE-1;
@@ -1521,7 +1521,7 @@ static void R_RenderSegLoop (void)
 				else
 					xwalllights = scalelight[lightnum];
 
-				pindex = FixedMul(rw_scale, FixedDiv(640, vid.width))>>LIGHTSCALESHIFT;
+				pindex = FixedMul(rw_scale, LIGHTRESOLUTIONFIX)>>LIGHTSCALESHIFT;
 
 				if (pindex >=  MAXLIGHTSCALE)
 					pindex = MAXLIGHTSCALE-1;
diff --git a/src/r_things.c b/src/r_things.c
index bb98d7f15..cb9d78464 100644
--- a/src/r_things.c
+++ b/src/r_things.c
@@ -1097,7 +1097,7 @@ static void R_SplitSprite(vissprite_t *sprite)
 			if (!((newsprite->cut & SC_FULLBRIGHT)
 				&& (!newsprite->extra_colormap || !(newsprite->extra_colormap->fog & 1))))
 			{
-				lindex = FixedMul(sprite->xscale, FixedDiv(640, vid.width))>>(LIGHTSCALESHIFT);
+				lindex = FixedMul(sprite->xscale, LIGHTRESOLUTIONFIX)>>(LIGHTSCALESHIFT);
 
 				if (lindex >= MAXLIGHTSCALE)
 					lindex = MAXLIGHTSCALE-1;
@@ -1872,7 +1872,7 @@ static void R_ProjectSprite(mobj_t *thing)
 	else
 	{
 		// diminished light
-		lindex = FixedMul(xscale, FixedDiv(640, vid.width))>>(LIGHTSCALESHIFT);
+		lindex = FixedMul(xscale, LIGHTRESOLUTIONFIX)>>(LIGHTSCALESHIFT);
 
 		if (lindex >= MAXLIGHTSCALE)
 			lindex = MAXLIGHTSCALE-1;