diff --git a/src/hardware/hw_main.c b/src/hardware/hw_main.c
index c70b6dd01..f395a8390 100644
--- a/src/hardware/hw_main.c
+++ b/src/hardware/hw_main.c
@@ -309,39 +309,39 @@ static FUINT HWR_CalcSlopeLight(FUINT lightnum, angle_t dir, fixed_t delta)
 	return (FUINT)finallight;
 }
 
-static FUINT HWR_SideLightLevel(side_t *side, UINT8 base_lightlevel)
+static UINT8 HWR_SideLightLevel(side_t *side, INT16 base_lightlevel)
 {
-	return side->light +
-		((side->lightabsolute) ? 0 : base_lightlevel);
+	return max(0, min(255, side->light +
+		((side->lightabsolute) ? 0 : base_lightlevel)));
 }
 
 /* TODO: implement per-texture lighting
-static FUINT HWR_TopLightLevel(side_t *side, UINT8 base_lightlevel)
+static UINT8 HWR_TopLightLevel(side_t *side, INT16 base_lightlevel)
 {
-	return side->light_top +
-		((side->lightabsolute_top) ? 0 : HWR_SideLightLevel(side, base_lightlevel));
+	return max(0, min(255, side->light_top +
+		((side->lightabsolute_top) ? 0 : HWR_SideLightLevel(side, base_lightlevel))));
 }
 
-static FUINT HWR_MidLightLevel(side_t *side, UINT8 base_lightlevel)
+static UINT8 HWR_MidLightLevel(side_t *side, INT16 base_lightlevel)
 {
-	return side->light_mid +
-		((side->lightabsolute_mid) ? 0 : HWR_SideLightLevel(side, base_lightlevel));
+	return max(0, min(255, side->light_mid +
+		((side->lightabsolute_mid) ? 0 : HWR_SideLightLevel(side, base_lightlevel))));
 }
 
-static FUINT HWR_BottomLightLevel(side_t *side, UINT8 base_lightlevel)
+static UINT8 HWR_BottomLightLevel(side_t *side, INT16 base_lightlevel)
 {
-	return side->light_bottom +
-		((side->lightabsolute_bottom) ? 0 : HWR_SideLightLevel(side, base_lightlevel));
+	return max(0, min(255, side->light_bottom +
+		((side->lightabsolute_bottom) ? 0 : HWR_SideLightLevel(side, base_lightlevel))));
 }
 */
 
-static UINT8 HWR_FloorLightLevel(sector_t *sector, UINT8 base_lightlevel)
+static UINT8 HWR_FloorLightLevel(sector_t *sector, INT16 base_lightlevel)
 {
 	return max(0, min(255, sector->floorlightlevel +
 		((sector->floorlightabsolute) ? 0 : base_lightlevel)));
 }
 
-static UINT8 HWR_CeilingLightLevel(sector_t *sector, UINT8 base_lightlevel)
+static UINT8 HWR_CeilingLightLevel(sector_t *sector, INT16 base_lightlevel)
 {
 	return max(0, min(255, sector->ceilinglightlevel +
 		((sector->ceilinglightabsolute) ? 0 : base_lightlevel)));
diff --git a/src/r_bsp.c b/src/r_bsp.c
index 4b4c81b88..373a170c9 100644
--- a/src/r_bsp.c
+++ b/src/r_bsp.c
@@ -230,13 +230,13 @@ static INT32 R_DoorClosed(void)
 	&& (backsector->floorheight <= frontsector->floorheight || curline->sidedef->bottomtexture);
 }
 
-static UINT8 R_FloorLightLevel(sector_t *sector, UINT8 base_lightlevel)
+static UINT8 R_FloorLightLevel(sector_t *sector, INT16 base_lightlevel)
 {
 	return max(0, min(255, sector->floorlightlevel +
 		((sector->floorlightabsolute) ? 0 : base_lightlevel)));
 }
 
-static UINT8 R_CeilingLightLevel(sector_t *sector, UINT8 base_lightlevel)
+static UINT8 R_CeilingLightLevel(sector_t *sector, INT16 base_lightlevel)
 {
 	return max(0, min(255, sector->ceilinglightlevel +
 		((sector->ceilinglightabsolute) ? 0 : base_lightlevel)));
diff --git a/src/r_segs.c b/src/r_segs.c
index 637e528fe..a8a065c9b 100644
--- a/src/r_segs.c
+++ b/src/r_segs.c
@@ -94,29 +94,29 @@ transnum_t R_GetLinedefTransTable(fixed_t alpha)
 	return (20*(FRACUNIT - alpha - 1) + FRACUNIT) >> (FRACBITS+1);
 }
 
-static INT16 R_SideLightLevel(side_t *side, UINT8 base_lightlevel)
+static UINT8 R_SideLightLevel(side_t *side, INT16 base_lightlevel)
 {
-	return side->light +
-		((side->lightabsolute) ? 0 : base_lightlevel);
+	return max(0, min(255, side->light +
+		((side->lightabsolute) ? 0 : base_lightlevel)));
 }
 
 /* TODO: implement per-texture lighting
-static INT16 R_TopLightLevel(side_t *side, UINT8 base_lightlevel)
+static UINT8 R_TopLightLevel(side_t *side, INT16 base_lightlevel)
 {
-	return side->light_top +
-		((side->lightabsolute_top) ? 0 : R_SideLightLevel(side, base_lightlevel));
+	return max(0, min(255, side->light_top +
+		((side->lightabsolute_top) ? 0 : R_SideLightLevel(side, base_lightlevel))));
 }
 
-static INT16 R_MidLightLevel(side_t *side, UINT8 base_lightlevel)
+static UINT8 R_MidLightLevel(side_t *side, INT16 base_lightlevel)
 {
-	return side->light_mid +
-		((side->lightabsolute_mid) ? 0 : R_SideLightLevel(side, base_lightlevel));
+	return max(0, min(255, side->light_mid +
+		((side->lightabsolute_mid) ? 0 : R_SideLightLevel(side, base_lightlevel))));
 }
 
-static INT16 R_BottomLightLevel(side_t *side, UINT8 base_lightlevel)
+static UINT8 R_BottomLightLevel(side_t *side, INT16 base_lightlevel)
 {
-	return side->light_bottom +
-		((side->lightabsolute_bottom) ? 0 : R_SideLightLevel(side, base_lightlevel));
+	return max(0, min(255, side->light_bottom +
+		((side->lightabsolute_bottom) ? 0 : R_SideLightLevel(side, base_lightlevel))));
 }
 */