diff --git a/eval/builtin_func.go b/eval/builtin_func.go
index 51a0579d..83582f26 100644
--- a/eval/builtin_func.go
+++ b/eval/builtin_func.go
@@ -40,6 +40,7 @@ func init() {
 		&BuiltinFn{"typeof", typeof},
 
 		&BuiltinFn{"fail", wrapFn(fail)},
+		&BuiltinFn{"multi-error", wrapFn(multiErrorFn)},
 		&BuiltinFn{"return", wrapFn(returnFn)},
 		&BuiltinFn{"break", wrapFn(breakFn)},
 		&BuiltinFn{"continue", wrapFn(continueFn)},
@@ -191,6 +192,10 @@ func fail(ec *evalCtx, arg Value) {
 	throw(errors.New(ToString(arg)))
 }
 
+func multiErrorFn(ec *evalCtx, args ...Error) {
+	throw(multiError{args})
+}
+
 func returnFn(ec *evalCtx) {
 	throw(Return)
 }
diff --git a/eval/value.go b/eval/value.go
index e55000ce..8d536e4f 100644
--- a/eval/value.go
+++ b/eval/value.go
@@ -179,7 +179,7 @@ type multiError struct {
 
 func (me multiError) Repr() string {
 	b := new(bytes.Buffer)
-	b.WriteString("(multi-error")
+	b.WriteString("?(multi-error")
 	for _, e := range me.errors {
 		b.WriteString(" ")
 		b.WriteString(e.Repr())