diff --git a/ccache.h b/ccache.h
index faec597..7ae4351 100644
--- a/ccache.h
+++ b/ccache.h
@@ -6,11 +6,10 @@
 #include <unistd.h>
 #include <stdlib.h>
 #include <errno.h>
-#include <sys/stat.h>
 #include <sys/types.h>
+#include <sys/stat.h>
 #include <sys/wait.h>
 #include <sys/mman.h>
-#include <sys/file.h>
 #include <fcntl.h>
 #include <time.h>
 #include <string.h>
@@ -19,6 +18,7 @@
 #include <stdarg.h>
 #include <dirent.h>
 #include <limits.h>
+#include <sys/file.h>
 #ifdef HAVE_PWD_H
 #include <pwd.h>
 #endif
diff --git a/config.h.in b/config.h.in
index f62239e..ffaf158 100644
--- a/config.h.in
+++ b/config.h.in
@@ -107,5 +107,5 @@
 
 /* Define on UNIX to activate XPG/5 features.  */
 #if !defined(_XOPEN_SOURCE)
-# define _XOPEN_SOURCE 500
+# define _XOPEN_SOURCE
 #endif
diff --git a/configure.in b/configure.in
index 321c592..fbeb976 100644
--- a/configure.in
+++ b/configure.in
@@ -20,7 +20,7 @@ AC_DEFINE([_GNU_SOURCE], 1,
 AH_VERBATIM([_XOPEN_SOURCE],
 [/* Define on UNIX to activate XPG/5 features.  */
 #if !defined(_XOPEN_SOURCE)
-# define _XOPEN_SOURCE 500
+# define _XOPEN_SOURCE
 #endif])
 
 # If GCC, turn on warnings.