diff --git a/Makefile b/Makefile
index 0bf04f4..54f3ba4 100644
--- a/Makefile
+++ b/Makefile
@@ -378,7 +378,7 @@
   set_target_defaults = $(call default_opts, \
     USE_POLL USE_TPROXY USE_LIBCRYPT USE_CRYPT_H USE_GETADDRINFO USE_THREAD \
     USE_RT USE_OBSOLETE_LINKER USE_EVPORTS USE_CLOSEFROM)
-  TARGET_CFLAGS  = -DFD_SETSIZE=65536 -D_REENTRANT -D_XOPEN_SOURCE=500 -D__EXTENSIONS__
+  TARGET_CFLAGS  = -DFD_SETSIZE=65536 -D_REENTRANT -D_XOPEN_SOURCE=600 -D__EXTENSIONS__
   TARGET_LDFLAGS = -lnsl -lsocket
 endif