diff --git a/Quake/r_brush.c b/Quake/r_brush.c
index 991d2ab9..14999089 100644
--- a/Quake/r_brush.c
+++ b/Quake/r_brush.c
@@ -726,6 +726,8 @@ int AllocBlock (int w, int h, int *x, int *y)
 			lightmap_count++;
 			lightmap = (struct lightmap_s *) realloc(lightmap, sizeof(*lightmap)*lightmap_count);
 			memset(&lightmap[texnum], 0, sizeof(lightmap[texnum]));
+			/* FIXME: we leave 'gaps' in malloc()ed data,  CRC_Block() later accesses
+			 * that uninitialized data and valgrind complains for it.  use calloc() ? */
 			lightmap[texnum].data = (byte *) malloc(4*LMBLOCK_WIDTH*LMBLOCK_HEIGHT);
 			//as we're only tracking one texture, we don't need multiple copies of allocated any more.
 			memset(allocated, 0, sizeof(allocated));