diff --git a/config.h.in b/config.h.in
index e4cdc9b9df..009515ef7f 100644
--- a/config.h.in
+++ b/config.h.in
@@ -16,7 +16,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: config.h.in,v 1.118 2009/09/01 00:22:24 jinmei Exp $ */
+/* $Id: config.h.in,v 1.119 2009/09/01 17:54:16 jinmei Exp $ */
 
 /*! \file */
 
@@ -298,6 +298,9 @@ int sigwait(const unsigned int *set, int *sig);
 /* Define to the flags type used by getnameinfo(3). */
 #undef IRS_GETNAMEINFO_FLAGS_T
 
+/* Define to the return type of gai_strerror(3). */
+#undef IRS_GAISTRERROR_RETURN_T
+
 /* Define if connect does not honour the permission on the UNIX domain socket.
    */
 #undef NEED_SECURE_DIRECTORY
diff --git a/configure.in b/configure.in
index 7f5bd3c135..11e79a334d 100644
--- a/configure.in
+++ b/configure.in
@@ -18,7 +18,7 @@ AC_DIVERT_PUSH(1)dnl
 esyscmd([sed "s/^/# /" COPYRIGHT])dnl
 AC_DIVERT_POP()dnl
 
-AC_REVISION($Revision: 1.474 $)
+AC_REVISION($Revision: 1.475 $)
 
 AC_INIT(lib/dns/name.c)
 AC_PREREQ(2.59)
@@ -1876,6 +1876,22 @@ int getnameinfo(const struct sockaddr *, socklen_t, char *,
 AC_DEFINE(IRS_GETNAMEINFO_BUFLEN_T, socklen_t)
 AC_DEFINE(IRS_GETNAMEINFO_FLAGS_T, int)])])
 
+#
+# ...and same for gai_strerror().
+#
+AC_MSG_CHECKING(for gai_strerror prototype definitions)
+AC_TRY_COMPILE([
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <netdb.h>
+char *gai_strerror(int ecode);],
+[ return (0); ],
+	[AC_MSG_RESULT(returning char *)
+	 AC_DEFINE([IRS_GAISTRERROR_RETURN_T], [char *],
+	 [return type of gai_srerror])],
+[AC_MSG_RESULT(not match any subspecies; assume standard definition)])
+AC_DEFINE([IRS_GAISTRERROR_RETURN_T], [const char *])
+
 AC_CHECK_FUNC(getipnodebyname,
 	[ISC_LWRES_GETIPNODEPROTO="#undef ISC_LWRES_GETIPNODEPROTO"],
 	[ISC_LWRES_GETIPNODEPROTO="#define ISC_LWRES_GETIPNODEPROTO 1"])
diff --git a/lib/irs/gai_strerror.c b/lib/irs/gai_strerror.c
index edae6613a8..df8bf024d4 100644
--- a/lib/irs/gai_strerror.c
+++ b/lib/irs/gai_strerror.c
@@ -15,7 +15,7 @@
  * PERFORMANCE OF THIS SOFTWARE.
  */
 
-/* $Id: gai_strerror.c,v 1.3 2009/09/01 03:43:27 jinmei Exp $ */
+/* $Id: gai_strerror.c,v 1.4 2009/09/01 17:54:16 jinmei Exp $ */
 
 /*! \file gai_strerror.c
  * gai_strerror() returns an error message corresponding to an
@@ -78,7 +78,7 @@ static const char *gai_messages[] = {
  * Returns an error message corresponding to an error code returned by
  * getaddrinfo() and getnameinfo()
  */
-const char *
+IRS_GAISTRERROR_RETURN_T
 gai_strerror(int ecode) {
 	union {
 		const char *const_ptr;