diff --git a/libc/bionic/dlmalloc.h b/libc/bionic/dlmalloc.h
index a00a583..71b3be8 100644
--- a/libc/bionic/dlmalloc.h
+++ b/libc/bionic/dlmalloc.h
@@ -27,6 +27,7 @@
 #define LOCK_AT_FORK 1
 #define USE_RECURSIVE_LOCK 0
 #define USE_SPIN_LOCKS 0
+#define DEFAULT_MMAP_THRESHOLD (64U * 1024U)
 
 /* Include the proper definitions. */
 #include "../upstream-dlmalloc/malloc.h"