diff --git a/build_maxlen_filter.sh b/build_maxlen_filter.sh
index 6c99d42..2cb458c 100755
--- a/build_maxlen_filter.sh
+++ b/build_maxlen_filter.sh
@@ -12,6 +12,7 @@ if [ ! "$1" ]; then
     echo "babeld - [with-deny]"
     echo "babeld-uci  - [with-deny]"
     echo "bird - [prefix-list]"
+    echo "yaml"
     exit 1
 fi
 
@@ -41,6 +42,8 @@ for file in *.json; do
             if [ "$2" == "with-deny" ]; then
                 filter="${filter}config filter\n\toption 'type'\t'in'\n\toption 'ip'\t'$prefix'\n\toption 'action'\t'deny'\n\n"
             fi
+        elif [ "$1" == "yaml" ]; then
+            filter="${filter}- prefix: $prefix\n  maxlen: $maxlen\n"
         fi
     done
 done
@@ -52,7 +55,7 @@ elif [ "$1" == "babeld-uci" ]; then
     filter=${filter::-4}
 elif [ "$1" == "bird" ]; then
     filter=${filter::-3}
-elif [ "$1" == "babeld" ]; then
+elif [ "$1" == "babeld" ] || [ "$1" == "yaml" ]; then
     filter=${filter::-2}
 fi