diff --git a/src/c/dlmalloc.c b/src/c/dlmalloc.c
index 6ad2b06274..efdfd21142 100644
--- a/src/c/dlmalloc.c
+++ b/src/c/dlmalloc.c
@@ -557,6 +557,7 @@ extern __thread int errno;
 #endif /*defined(__redox__)*/
 
 #define MAP_PRIVATE 2
+#define MAP_ANON 32
 typedef long off_t;
 
 int open(const char *pathname, int flags);