diff --git a/src/hardware/hw_main.c b/src/hardware/hw_main.c
index 976d210c2..145a6b464 100644
--- a/src/hardware/hw_main.c
+++ b/src/hardware/hw_main.c
@@ -310,7 +310,7 @@ static FUINT HWR_CalcSlopeLight(FUINT lightnum, pslope_t *slope, const sector_t
 {
 	INT16 finallight = lightnum;
 
-	if (slope != NULL && P_ApplyLightOffsetFine(lightnum, sector))
+	if (slope != NULL && sector != NULL && P_ApplyLightOffsetFine(lightnum, sector))
 	{
 		finallight += slope->hwLightOffset;