diff --git a/src/allocator_thread.c b/src/allocator_thread.c
index f9b2c91..cb4e987 100644
--- a/src/allocator_thread.c
+++ b/src/allocator_thread.c
@@ -2,6 +2,7 @@
 #define _GNU_SOURCE
 #undef _POSIX_C_SOURCE
 #define _POSIX_C_SOURCE 200809L
+#define _DARWIN_C_SOURCE
 #include <limits.h>
 #include <pthread.h>
 #include <unistd.h>