diff --git a/ChangeLog b/ChangeLog
index a11a5c628f..f1abd7a05d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Tue Apr 16 23:07:12 2013  Tanaka Akira  <akr@fsij.org>
+
+	* ext/socket/unixsocket.c (unix_send_io): Suppress a warning by clang.
+	  (unix_recv_io): Ditto.
+
 Tue Apr 16 12:27:00 2013  Zachary Scott  <zachary@zacharyscott.net>
 
 	* ext/sdbm/init.c: Fix comment indentation, by windwiny [Fixes GH-277]
diff --git a/ext/socket/unixsocket.c b/ext/socket/unixsocket.c
index 3d3fc889e1..38cfa7aa94 100644
--- a/ext/socket/unixsocket.c
+++ b/ext/socket/unixsocket.c
@@ -208,9 +208,9 @@ unix_send_io(VALUE sock, VALUE val)
     char buf[1];
 
 #if FD_PASSING_BY_MSG_CONTROL
-    struct {
+    union {
 	struct cmsghdr hdr;
-	char pad[8+sizeof(int)+8];
+	char pad[sizeof(struct cmsghdr)+8+sizeof(int)+8];
     } cmsg;
 #endif
 
@@ -303,9 +303,9 @@ unix_recv_io(int argc, VALUE *argv, VALUE sock)
 
     int fd;
 #if FD_PASSING_BY_MSG_CONTROL
-    struct {
+    union {
 	struct cmsghdr hdr;
-	char pad[8+sizeof(int)+8];
+	char pad[sizeof(struct cmsghdr)+8+sizeof(int)+8];
     } cmsg;
 #endif