diff --git a/lib/logstorage/filter_and.go b/lib/logstorage/filter_and.go
index 27a9125b0..5d46151db 100644
--- a/lib/logstorage/filter_and.go
+++ b/lib/logstorage/filter_and.go
@@ -27,8 +27,7 @@ func (fa *filterAnd) String() string {
 	a := make([]string, len(filters))
 	for i, f := range filters {
 		s := f.String()
-		switch f.(type) {
-		case *filterOr:
+		if _, ok := f.(*filterOr); ok {
 			s = "(" + s + ")"
 		}
 		a[i] = s
diff --git a/lib/logstorage/parser_test.go b/lib/logstorage/parser_test.go
index e7e773a7d..f31d0b2e3 100644
--- a/lib/logstorage/parser_test.go
+++ b/lib/logstorage/parser_test.go
@@ -594,6 +594,10 @@ func TestParseQuerySuccess(t *testing.T) {
 	f(`NOT foo AND bar OR baz`, `!foo bar or baz`)
 	f(`NOT (foo AND bar) OR baz`, `!(foo bar) or baz`)
 	f(`foo OR bar AND baz`, `foo or bar baz`)
+	f(`foo bar or baz xyz`, `foo bar or baz xyz`)
+	f(`foo (bar or baz) xyz`, `foo (bar or baz) xyz`)
+	f(`foo or bar baz or xyz`, `foo or bar baz or xyz`)
+	f(`(foo or bar) (baz or xyz)`, `(foo or bar) (baz or xyz)`)
 	f(`(foo OR bar) AND baz`, `(foo or bar) baz`)
 
 	// parens