AC_MSG_CHECKING([whether we are using the IBM C compiler])
CURL_CHECK_DEF([__IBMC__], [], [silent])
-if test "$curl_cv_have_def___IBMC__" = "yes"; then
+CURL_CHECK_DEF([__IBMCPP__], [], [silent])
+if test "$curl_cv_have_def___IBMC__" = "yes" ||
+ test "$curl_cv_have_def___IBMCPP__" = "yes"; then
AC_MSG_RESULT([yes])
dnl Ensure that compiler optimizations are always thread-safe.
CFLAGS="$CFLAGS -qthreaded"
AC_MSG_CHECKING([whether we are using the IBM C compiler])
CURL_CHECK_DEF([__IBMC__], [], [silent])
-if test "$curl_cv_have_def___IBMC__" = "yes"; then
+CURL_CHECK_DEF([__IBMCPP__], [], [silent])
+if test "$curl_cv_have_def___IBMC__" = "yes" ||
+ test "$curl_cv_have_def___IBMCPP__" = "yes"; then
AC_MSG_RESULT([yes])
dnl Ensure that compiler optimizations are always thread-safe.
CFLAGS="$CFLAGS -qthreaded"