diff --git a/ChangeLog b/ChangeLog
index e82caf06b2..dbd2e72f45 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue May  7 12:10:52 2013  Tanaka Akira  <akr@fsij.org>
+
+	* ext/socket/socket.c (socket_s_ip_address_list): Cast EXTRA_SPACE as
+	  int.  This suppress a warning.
+
 Tue May  7 12:09:29 2013  Tanaka Akira  <akr@fsij.org>
 
 	* ext/socket/extconf.rb: Set close_fds false for Cygwin.
diff --git a/ext/socket/socket.c b/ext/socket/socket.c
index a0c9618ce4..43bff85737 100644
--- a/ext/socket/socket.c
+++ b/ext/socket/socket.c
@@ -1759,7 +1759,7 @@ socket_s_ip_address_list(VALUE self)
 #elif defined(SIOCGIFCONF)
     int fd = -1;
     int ret;
-#define EXTRA_SPACE (sizeof(struct ifconf) + sizeof(union_sockaddr))
+#define EXTRA_SPACE ((int)(sizeof(struct ifconf) + sizeof(union_sockaddr)))
     char initbuf[4096+EXTRA_SPACE];
     char *buf = initbuf;
     int bufsize;