OS X `leaks` command doesn't detect leaks from anonymous mmap()s

anon_mmap.c

#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <unistd.h>

int main() {
  void *buf = mmap(NULL, 1024, PROT_WRITE, MAP_ANON | MAP_SHARED, -1, 0);
  strcpy(buf, "TESTING 123");
  printf("Buf is '%s'\n", buf);
  buf = NULL;
  if (buf != NULL) {
    printf("OMG WTF");
  }
  unsigned int sleep_time = 100;
  printf("Run...\nsudo leaks %u\n...in the next %u seconds\n", getpid(), sleep_time);
  sleep(sleep_time);
  printf("Done sleeping. Buh-bye!\n");
  return 0;
}

Terminal 1

ggreer@carbon:~/Desktop% gcc anon_mmap.c -o anon_mmap
ggreer@carbon:~/Desktop% ./anon_mmap 
Buf is 'TESTING 123'
Run...
sudo leaks 48974
...in the next 100 seconds

Terminal 2

ggreer@carbon:~% sudo leaks 48974
Process:         anon_mmap [48974]
Path:            /Users/ggreer/Desktop/anon_mmap
Load Address:    0
Identifier:      anon_mmap
Version:         ???
Code Type:       X86-64
Parent Process:  zsh [48029]

Date/Time:       2015-05-22 12:16:41.159 -0700
OS Version:      Mac OS X 10.10.3 (14D136)
Report Version:  7
Analysis Tool:   /Applications/Xcode.app/Contents/Developer/usr/bin/leaks
Analysis Tool Version:  Xcode 6.3.2 (6D2105)
----

leaks Report Version:  2.0
Process 48974: 402 nodes malloced for 32 KB
Process 48974: 0 leaks for 0 total leaked bytes.
ggreer@carbon:~%