diff --git a/include/unistd.h b/include/unistd.h
index 09891a7..58e9ce7 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -21,7 +21,7 @@
 #endif
 
 #ifndef _XOPEN_VERSION
-/* we having this (define _XOPEN_VERSION 700) or not? */
+#define _XOPEN_VERSION 700
 #endif
 
 /*