diff --git a/libc/upstream-openbsd/openbsd-compat.h b/libc/upstream-openbsd/openbsd-compat.h
index 428156f..2c3fe56 100644
--- a/libc/upstream-openbsd/openbsd-compat.h
+++ b/libc/upstream-openbsd/openbsd-compat.h
@@ -18,5 +18,6 @@
 #define _BIONIC_OPENBSD_COMPAT_H_included
 
 #define _GNU_SOURCE
+#define __USE_BSD
 
 #endif