diff --git a/macros/ac_pkg_swig.m4 b/macros/ac_pkg_swig.m4
index 406bc4b32b..f0f3389e83 100644
--- a/macros/ac_pkg_swig.m4
+++ b/macros/ac_pkg_swig.m4
@@ -28,7 +28,7 @@ dnl @license GPLWithACException
 AC_DEFUN([AC_PROG_SWIG],[
         AC_PATH_PROG([SWIG],[swig])
         if test -z "$SWIG" ; then
-                AC_MSG_WARN([cannot find 'swig' program. You should look at http://www.swig.org])
+                AC_MSG_ERROR([cannot find 'swig' program. You should look at http://www.swig.org])
                 SWIG='echo "Error: SWIG is not installed. You should look at http://www.swig.org" ; false'
         elif test -n "$1" ; then
                 AC_MSG_CHECKING([for SWIG version])