diff --git a/source/zone.c b/source/zone.c
index 1281d78..a8b6785 100644
--- a/source/zone.c
+++ b/source/zone.c
@@ -31,11 +31,12 @@
 #endif
 
 #include <stdlib.h>
+
 #ifdef HAVE_STRING_H
-#include <string.h>
+# include <string.h>
 #endif
 #ifdef HAVE_STRINGS_H
-#include <strings.h>
+# include <strings.h>
 #endif
 
 #include "cmd.h"