diff --git a/src/os.c b/src/os.c
index e2c3c4a5..07ab6b1c 100644
--- a/src/os.c
+++ b/src/os.c
@@ -179,7 +179,11 @@ static void* mi_mmap(void* addr, size_t size, int extra_flags, mi_stats_t* stats
       flags |= MAP_FIXED;
     #endif
   }
-  p = mmap(addr, size, (PROT_READ | PROT_WRITE), flags, -1, 0);
+  int pflags = PROT_READ | PROT_WRITE;
+#if defined(PROT_MAX)
+  pflags |= PROT_MAX(PROT_READ | PROT_WRITE); // BSD
+#endif
+  p = mmap(addr, size, pflags, flags, -1, 0);
   if (p == MAP_FAILED) p = NULL;
   if (addr != NULL && p != addr) {
     mi_munmap(p, size);