diff --git a/code/renderergl1/tr_bsp.c b/code/renderergl1/tr_bsp.c
index 8e2b95af8..a4d35699d 100644
--- a/code/renderergl1/tr_bsp.c
+++ b/code/renderergl1/tr_bsp.c
@@ -1985,11 +1985,13 @@ void R_LoadLightGrid( const bspFile_t *bsp ) {
 		return;
 	}
 
-	w->lightGridData = bsp->lightGridData;
+	w->lightGridData = ri.Hunk_Alloc( bsp->numGridPoints * 8, h_low );
 	w->numGridPoints = bsp->numGridPoints;
 	w->lightGridArray = bsp->lightGridArray;
 	w->numGridArrayPoints = bsp->numGridArrayPoints;
 
+	Com_Memcpy( w->lightGridData, bsp->lightGridData, bsp->numGridPoints * 8 );
+
 	// deal with overbright bits
 	for ( i = 0 ; i < bsp->numGridPoints ; i++ ) {
 		R_ColorShiftLightingBytes( 4, &w->lightGridData[i*8], &w->lightGridData[i*8] );
diff --git a/code/renderergl2/tr_bsp.c b/code/renderergl2/tr_bsp.c
index f4b84cea9..3d68a7923 100644
--- a/code/renderergl2/tr_bsp.c
+++ b/code/renderergl2/tr_bsp.c
@@ -2533,11 +2533,13 @@ void R_LoadLightGrid( const bspFile_t *bsp ) {
 		return;
 	}
 
-	w->lightGridData = bsp->lightGridData;
+	w->lightGridData = ri.Hunk_Alloc( bsp->numGridPoints * 8, h_low );
 	w->numGridPoints = bsp->numGridPoints;
 	w->lightGridArray = bsp->lightGridArray;
 	w->numGridArrayPoints = bsp->numGridArrayPoints;
 
+	Com_Memcpy( w->lightGridData, bsp->lightGridData, bsp->numGridPoints * 8 );
+
 	// deal with overbright bits
 	for ( i = 0 ; i < bsp->numGridPoints ; i++ ) {
 		R_ColorShiftLightingBytes( 4, &w->lightGridData[i*8], &w->lightGridData[i*8] );