diff --git a/tile.h b/tile.h
index 5b1ff79..0612765 100644
--- a/tile.h
+++ b/tile.h
@@ -18,9 +18,9 @@ struct pool_val *deserialize_string(char **f, struct pool *p, int type);
 
 
 struct index {
-        unsigned long long index;
-        long long fpos;
-	int maxzoom;
+	unsigned long long index;
+	long long fpos : 56;
+	int maxzoom : 8;
 };
 
 long long write_tile(struct index *start, struct index *end, char *metabase, unsigned *file_bbox, int z, unsigned x, unsigned y, int detail, int basezoom, struct pool *file_keys, char *layername, sqlite3 *outdb, double droprate, int buffer);