--- a/configure.in
+++ b/configure.in
@@ -97,7 +97,7 @@
     version=`$apr_config --version`
     case x${version} in
     x1.[[0-3]].*) 
-      AC_MSG_WARN([APR version 1.4.0 or later is required, found $version])
+      AC_MSG_ERROR([APR version 1.4.0 or later is required, found $version])
       apr_acceptable=no
       ;;
     esac
