1 files changed, 3 insertions, 4 deletions
diff --git a/Src/mem.c b/Src/mem.c
index 62d18d0cd..e31145e1e 100644
--- a/Src/mem.c
+++ b/Src/mem.c
@@ -79,16 +79,15 @@
 
 #include <sys/mman.h>
 
-#if 0
 /*
- * This change was designed to enable use of memory mapping on MacOS.
+ * This definition is designed to enable use of memory mapping on MacOS.
  * However, performance tests indicate that MacOS mapped regions are
- * significantly slower to allocate than memory from malloc().
+ * somewhat slower to allocate than memory from malloc(), so whether
+ * using this improves performance depends on details of zhalloc().
  */
 #if defined(MAP_ANON) && !defined(MAP_ANONYMOUS)
 #define MAP_ANONYMOUS MAP_ANON
 #endif
-#endif /* 0 */
 
 #if defined(MAP_ANONYMOUS) && defined(MAP_PRIVATE)