diff --git a/tools/quake3/q3map2/bspfile_ibsp.cpp b/tools/quake3/q3map2/bspfile_ibsp.cpp
index 607224bc..373328c7 100644
--- a/tools/quake3/q3map2/bspfile_ibsp.cpp
+++ b/tools/quake3/q3map2/bspfile_ibsp.cpp
@@ -142,7 +142,7 @@ struct ibspDrawSurface_t
 			.numIndexes     = numIndexes,
 			.lightmapStyles { LS_NORMAL, LS_NONE, LS_NONE, LS_NONE },
 			.vertexStyles   { LS_NORMAL, LS_NONE, LS_NONE, LS_NONE },
-			.lightmapNum    { lightmapNum, -3, -3, -3 },
+			.lightmapNum    { lightmapNum, LIGHTMAP_BY_VERTEX, LIGHTMAP_BY_VERTEX, LIGHTMAP_BY_VERTEX },
 			.lightmapX      { lightmapX, 0, 0, 0 },
 			.lightmapY      { lightmapY, 0, 0, 0 },
 			.lightmapWidth  = lightmapWidth,
diff --git a/tools/quake3/q3map2/convert_bsp.cpp b/tools/quake3/q3map2/convert_bsp.cpp
index 2fb28bf6..39235f7f 100644
--- a/tools/quake3/q3map2/convert_bsp.cpp
+++ b/tools/quake3/q3map2/convert_bsp.cpp
@@ -746,7 +746,7 @@ int MergeBSPMain( Args& args ){
 			fog.brushNum += bspBrushes.size();
 
 		/* deduce max lm index, using bspLightBytes is insufficient for native external lightmaps */
-		int maxLmIndex = -3;
+		int maxLmIndex = LIGHTMAP_BY_VERTEX;
 		for( const auto& surf : bspDrawSurfaces )
 			for( auto index : surf.lightmapNum )
 				value_maximize( maxLmIndex, index );
diff --git a/tools/quake3/q3map2/light.cpp b/tools/quake3/q3map2/light.cpp
index 27ab045a..59b77124 100644
--- a/tools/quake3/q3map2/light.cpp
+++ b/tools/quake3/q3map2/light.cpp
@@ -1865,7 +1865,7 @@ static void WriteBSPFileAfterLight( const char *bspFileName ){
 
 				out.lightmapStyles.fill( LS_NONE );
 				out.vertexStyles.fill( LS_NONE );
-				out.lightmapNum.fill( -3 );
+				out.lightmapNum.fill( LIGHTMAP_BY_VERTEX );
 			}
 
 			bakDrawSurfaces.insert( bakDrawSurfaces.cend(), bspDrawSurfaces.cbegin(), bspDrawSurfaces.cend() );
@@ -1896,7 +1896,7 @@ static void WriteBSPFileAfterLight( const char *bspFileName ){
 			for( auto& ds : bspDrawSurfaces ){
 				if( ds.surfaceType == MST_PLANAR ){
 					ds.surfaceType = MST_TRIANGLE_SOUP;
-					ds.lightmapNum[ 0 ] = -3;
+					ds.lightmapNum[ 0 ] = LIGHTMAP_BY_VERTEX;
 				}
 			}
 		}
diff --git a/tools/quake3/q3map2/lightmaps_ydnar.cpp b/tools/quake3/q3map2/lightmaps_ydnar.cpp
index a59dd447..e2b7f2ee 100644
--- a/tools/quake3/q3map2/lightmaps_ydnar.cpp
+++ b/tools/quake3/q3map2/lightmaps_ydnar.cpp
@@ -1754,7 +1754,7 @@ static void SetupOutLightmap( rawLightmap_t *lm, outLightmap_t *olm ){
 		}
 	}
 	else{
-		olm->lightmapNum = -3;
+		olm->lightmapNum = LIGHTMAP_BY_VERTEX;
 	}
 
 	/* set external lightmap number */
@@ -1791,8 +1791,8 @@ static void FindOutLightmaps( rawLightmap_t *lm, bool fastAllocate ){
 	int xIncrement, yIncrement;
 
 
-	/* set default lightmap number (-3 = LIGHTMAP_BY_VERTEX) */
-	lm->outLightmapNums.fill( -3 );
+	/* set default lightmap number */
+	lm->outLightmapNums.fill( LIGHTMAP_BY_VERTEX );
 
 	/* can this lightmap be approximated with vertex color? */
 	if ( ApproximateLightmap( lm ) ) {
@@ -3027,7 +3027,7 @@ void StoreSurfaceLightmaps( bool fastAllocate, bool storeForReal ){
 			/* handle vertex lit or approximated surfaces */
 			else if ( lm == nullptr || lm->outLightmapNums[ 0 ] < 0 ) {
 				ds.lightmapStyles = ds.vertexStyles;
-				ds.lightmapNum.fill( -3 );
+				ds.lightmapNum.fill( LIGHTMAP_BY_VERTEX );
 			}
 
 			/* handle lightmapped surfaces */
@@ -3041,7 +3041,7 @@ void StoreSurfaceLightmaps( bool fastAllocate, bool storeForReal ){
 
 					/* handle unused style */
 					if ( lm->styles[ lightmapNum ] == LS_NONE || lm->outLightmapNums[ lightmapNum ] < 0 ) {
-						ds.lightmapNum[ lightmapNum ] = -3;
+						ds.lightmapNum[ lightmapNum ] = LIGHTMAP_BY_VERTEX;
 						continue;
 					}
 
diff --git a/tools/quake3/q3map2/q3map2.h b/tools/quake3/q3map2/q3map2.h
index 27783456..fd8fec1b 100644
--- a/tools/quake3/q3map2/q3map2.h
+++ b/tools/quake3/q3map2/q3map2.h
@@ -187,6 +187,7 @@ enum class EBrushType
 #define EXTERNAL_LIGHTMAP       "lm_%04d.tga"
 
 #define MAX_LIGHTMAPS           4           /* RBSP */
+#define LIGHTMAP_BY_VERTEX      -3
 #define MAX_SWITCHED_LIGHTS     32
 #define LS_NORMAL               0x00
 #define LS_UNUSED               0xFE
diff --git a/tools/quake3/q3map2/surface.cpp b/tools/quake3/q3map2/surface.cpp
index d80697e8..23a349d9 100644
--- a/tools/quake3/q3map2/surface.cpp
+++ b/tools/quake3/q3map2/surface.cpp
@@ -2001,7 +2001,7 @@ static void EmitFlareSurface( mapDrawSurface_t& ds ){
 	/* RBSP */
 	out.lightmapStyles = { byte( ds.lightStyle ), LS_NONE, LS_NONE, LS_NONE };
 	out.vertexStyles   = { byte( ds.lightStyle ), LS_NONE, LS_NONE, LS_NONE };
-	out.lightmapNum.fill( -3 );
+	out.lightmapNum.fill( LIGHTMAP_BY_VERTEX );
 
 	out.lightmapOrigin = ds.lightmapOrigin;          /* origin */
 	out.lightmapVecs[ 0 ] = ds.lightmapVecs[ 0 ];    /* color */
@@ -2075,7 +2075,7 @@ static void EmitPatchSurface( const entity_t& e, mapDrawSurface_t& ds ){
 	/* RBSP */
 	out.lightmapStyles = { LS_NORMAL, LS_NONE, LS_NONE, LS_NONE };
 	out.vertexStyles   = { LS_NORMAL, LS_NONE, LS_NONE, LS_NONE };
-	out.lightmapNum.fill( -3 );
+	out.lightmapNum.fill( LIGHTMAP_BY_VERTEX );
 
 	/* ydnar: gs mods: previously, the lod bounds were stored in lightmapVecs[ 0 ] and [ 1 ], moved to bounds[ 0 ] and [ 1 ] */
 	out.lightmapOrigin = ds.lightmapOrigin;
@@ -2376,7 +2376,7 @@ static void EmitTriangleSurface( mapDrawSurface_t& ds ){
 	/* RBSP */
 	out.lightmapStyles = { LS_NORMAL, LS_NONE, LS_NONE, LS_NONE };
 	out.vertexStyles   = { LS_NORMAL, LS_NONE, LS_NONE, LS_NONE };
-	out.lightmapNum.fill( -3 );
+	out.lightmapNum.fill( LIGHTMAP_BY_VERTEX );
 
 	/* lightmap vectors (lod bounds for patches) */
 	out.lightmapOrigin = ds.lightmapOrigin;