if no strerror_r prototype is found, we provide our own to prevent picky
compilers to warn
diff --git a/acinclude.m4 b/acinclude.m4
index 3bfb112..a582a4e 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -396,6 +396,17 @@
AC_MSG_RESULT(no))])])
if test "x$strerror_r" = "xyes"; then
+
+ dnl check if strerror_r is properly declared in the headers
+ AC_CHECK_DECL(strerror_r, ,
+ AC_DEFINE(HAVE_NO_STRERROR_R_DECL, 1, [we have no strerror_r() proto])
+,
+[#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+])
+
dnl determine if this strerror_r() is glibc or POSIX
AC_MSG_CHECKING([for a glibc strerror_r API])
AC_TRY_RUN([
diff --git a/lib/strerror.c b/lib/strerror.c
index 6cc8709..d5c80d1 100644
--- a/lib/strerror.c
+++ b/lib/strerror.c
@@ -32,6 +32,15 @@
#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>
+#ifdef HAVE_NO_STRERROR_R_DECL
+#ifdef HAVE_POSIX_STRERROR_R
+/* seen on AIX 5100-02 gcc 2.9 */
+extern int strerror_r(int errnum, char *strerrbuf, size_t buflen);
+#else
+extern char *strerror_r(int errnum, char *buf, size_t buflen);
+#endif
+#endif
+
const char *
curl_easy_strerror(CURLcode error)
{
