diff --git a/include/jemalloc/internal/jemalloc_internal_defs.h b/include/jemalloc/internal/jemalloc_internal_defs.h
index 9a8a0b6..7733a5e 100644
--- a/include/jemalloc/internal/jemalloc_internal_defs.h
+++ b/include/jemalloc/internal/jemalloc_internal_defs.h
@@ -157,7 +157,7 @@
  * later reuse.  This is disabled by default on Linux because common sequences
  * of mmap()/munmap() calls will cause virtual memory map holes.
  */
-#define JEMALLOC_MUNMAP 
+/* #undef JEMALLOC_MUNMAP */
 
 /* TLS is used to map arenas and magazine caches to threads. */
 /* #undef JEMALLOC_TLS */