diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index f5d8808d7..71386a06e 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,8 @@
+2012-10-10  Corinna Vinschen  <corinna@vinschen.de>
+
+	* include/cygwin/in.h (struct in_addr): Guard with s_addr to avoid
+	potential collision with Win32 headers.
+
 2012-10-09  Christopher Faylor  <me.cygwin2012@cgf.cx>
 
 	* child_info.h (child_info_spawn::has_execed): Remove unneeded
diff --git a/winsup/cygwin/include/cygwin/in.h b/winsup/cygwin/include/cygwin/in.h
index 49957293d..a64160e8f 100644
--- a/winsup/cygwin/include/cygwin/in.h
+++ b/winsup/cygwin/include/cygwin/in.h
@@ -112,11 +112,15 @@ enum
   IPPORT_USERRESERVED = 5000
 };
 
+/* Avoid collision with Mingw64 headers. */
+#ifndef s_addr
 /* Internet address. */
 struct in_addr
 {
   in_addr_t s_addr;
 };
+#define s_addr s_addr
+#endif
 
 /* Request struct for IPv4 multicast socket ops */