diff --git a/Makefile b/Makefile
index 99d6f51..ad280a3 100644
--- a/Makefile
+++ b/Makefile
@@ -5,6 +5,7 @@ include config.mk
 
 HDR =\
 	arg.h\
+	compat.h\
 	crypt.h\
 	fs.h\
 	md5.h\
diff --git a/compat.h b/compat.h
new file mode 100644
index 0000000..e2154a6
--- /dev/null
+++ b/compat.h
@@ -0,0 +1,6 @@
+/* See LICENSE file for copyright and license details. */
+#include <limits.h>
+
+#ifndef HOST_NAME_MAX
+#define HOST_NAME_MAX _POSIX_HOST_NAME_MAX
+#endif
diff --git a/util.h b/util.h
index b152ffd..2de6f3b 100644
--- a/util.h
+++ b/util.h
@@ -1,13 +1,11 @@
 /* See LICENSE file for copyright and license details. */
 #include <sys/types.h>
-#include <limits.h>
+
 #include <regex.h>
 #include <stddef.h>
-#include "arg.h"
 
-#ifndef HOST_NAME_MAX
-#define HOST_NAME_MAX _POSIX_HOST_NAME_MAX
-#endif
+#include "arg.h"
+#include "compat.h"
 
 #define UTF8_POINT(c) (((c) & 0xc0) != 0x80)