diff --git a/ChangeLog b/ChangeLog
index 9fc94ebd6f..3e0b27927d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Sat Jun 11 10:00:49 2011  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* ruby.c (ruby_process_options): add missing return type.
+
 Fri Jun 10 23:18:09 2011  KOSAKI Motohiro  <kosaki.motohiro@gmail.com>
 
 	* ext/tk/tcltklib.c (lib_eventloop_core): replace CHECK_INTS with
diff --git a/ruby.c b/ruby.c
index 0cd847795d..4976ba185f 100644
--- a/ruby.c
+++ b/ruby.c
@@ -1802,7 +1802,7 @@ ruby_process_options(int argc, char **argv)
 
 #ifndef HAVE_SETPROCTITLE
     {
-	extern compat_init_setproctitle(int argc, char *argv[]);
+	extern void compat_init_setproctitle(int argc, char *argv[]);
 	compat_init_setproctitle(argc, argv);
     }
 #endif