diff --git a/filter/config.Y b/filter/config.Y
index 6783ea10..79247ac9 100644
--- a/filter/config.Y
+++ b/filter/config.Y
@@ -279,7 +279,7 @@ CF_KEYWORDS(FUNCTION, PRINT, PRINTN, UNSET, RETURN,
 	FROM, GW, NET, MASK, PROTO, SOURCE, SCOPE, CAST, DEST, IFNAME, IFINDEX,
 	PREFERENCE,
 	ROA_CHECK, ASN,
-	LEN,
+	LEN, MAXLEN,
 	DEFINED,
 	ADD, DELETE, CONTAINS, RESET,
 	PREPEND, FIRST, LAST, LAST_NONAGGREGATED, MATCH,
@@ -740,6 +740,7 @@ term:
 
  | term '.' IP { $$ = f_new_inst(); $$->code = P('c','p'); $$->a1.p = $1; $$->aux = T_IP; }
  | term '.' LEN { $$ = f_new_inst(); $$->code = 'L'; $$->a1.p = $1; }
+ | term '.' MAXLEN { $$ = f_new_inst(); $$->code = P('R','m'); $$->a1.p = $1; }
  | term '.' ASN { $$ = f_new_inst(); $$->code = P('R','a'); $$->a1.p = $1; }
  | term '.' MASK '(' term ')' { $$ = f_new_inst(); $$->code = P('i','M'); $$->a1.p = $1; $$->a2.p = $5; }
  | term '.' FIRST { $$ = f_new_inst(); $$->code = P('a','f'); $$->a1.p = $1; }
diff --git a/filter/filter.c b/filter/filter.c
index ba1ba753..ebdd02f2 100644
--- a/filter/filter.c
+++ b/filter/filter.c
@@ -1029,6 +1029,16 @@ interpret(struct f_inst *what)
     default: runtime( "Prefix, path, clist or eclist expected" );
     }
     break;
+  case P('R','m'): 	/* Get ROA max prefix length */
+    ONEARG;
+    if (v1.type != T_NET || !net_is_roa(v1.val.net))
+      runtime( "ROA expected" );
+
+    res.type = T_INT;
+    res.val.i = (v1.val.net->type == NET_ROA4) ?
+      ((net_addr_roa4 *) v1.val.net)->max_pxlen :
+      ((net_addr_roa6 *) v1.val.net)->max_pxlen;
+    break;
   case P('R','a'): 	/* Get ROA ASN */
     ONEARG;
     if (v1.type != T_NET || !net_is_roa(v1.val.net))