diff --git a/filter/config.Y b/filter/config.Y
index ec29ea7e..eecebf61 100644
--- a/filter/config.Y
+++ b/filter/config.Y
@@ -406,7 +406,7 @@ CF_KEYWORDS(FUNCTION, PRINT, PRINTN, UNSET, RETURN,
 	PREPEND, FIRST, LAST, LAST_NONAGGREGATED, MATCH,
 	EMPTY,
 	FILTER, WHERE, EVAL,
-	BT_ASSERT, BT_TEST_SUITE)
+	BT_ASSERT, BT_TEST_SUITE, FORMAT)
 
 %nonassoc THEN
 %nonassoc ELSE
@@ -916,6 +916,7 @@ term:
  | ROA_CHECK '(' rtable ')' { $$ = f_generate_roa_check($3, NULL, NULL); }
  | ROA_CHECK '(' rtable ',' term ',' term ')' { $$ = f_generate_roa_check($3, $5, $7); }
 
+ | FORMAT '(' term ')' {  $$ = f_new_inst(); $$->code = P('f','m'); $$->a1.p = $3; }
 
 /* | term '.' LEN { $$->code = P('P','l'); } */
 
diff --git a/filter/filter.c b/filter/filter.c
index 88d138a0..145ff4b3 100644
--- a/filter/filter.c
+++ b/filter/filter.c
@@ -563,6 +563,14 @@ f_rta_cow(void)
   (*f_rte)->attrs = rta_do_cow((*f_rte)->attrs, f_pool);
 }
 
+static char *
+val_format_str(struct f_val v) {
+  buffer b;
+  LOG_BUFFER_INIT(b);
+  val_format(v, &b);
+  return lp_strdup(f_pool, b.start);
+}
+
 static struct tbf rl_runtime_err = TBF_DEFAULT_LOG_LIMITS;
 
 #define runtime(fmt, ...) do { \
@@ -1477,6 +1485,13 @@ interpret(struct f_inst *what)
 
     break;
 
+  case P('f','m'):	/* Format */
+    ONEARG;
+
+    res.type = T_STRING;
+    res.val.s = val_format_str(v1);
+    break;
+
   case P('a','s'):	/* Birdtest Assert */
     ONEARG;