diff --git a/pkg/logql/log/filter.go b/pkg/logql/log/filter.go
index 92097c44dfe9e..5f5eff6b2ff89 100644
--- a/pkg/logql/log/filter.go
+++ b/pkg/logql/log/filter.go
@@ -307,11 +307,16 @@ type orFilter struct {
 
 // newOrFilter creates a new filter which matches only if left or right matches.
 func newOrFilter(left MatcherFilterer, right MatcherFilterer) MatcherFilterer {
-	if left == nil || isTrueFilter(left) {
-		return right
+	// If either side matches all, OR matches all.
+	if isTrueFilter(left) || isTrueFilter(right) {
+		return TrueFilter
 	}
 
-	if right == nil || isTrueFilter(right) {
+	// nil behaves as false: nil OR X = X.
+	if left == nil {
+		return right
+	}
+	if right == nil {
 		return left
 	}
 
diff --git a/pkg/logql/log/filter_test.go b/pkg/logql/log/filter_test.go
index b364ee2888e7f..19ade3066fcb2 100644
--- a/pkg/logql/log/filter_test.go
+++ b/pkg/logql/log/filter_test.go
@@ -159,6 +159,21 @@ func Test_TrueFilter(t *testing.T) {
 	}
 }
 
+func Test_OrFilterWithEmptyString(t *testing.T) {
+	// empty string produces TrueFilter
+	notfoundFilter := newContainsFilter([]byte("notfound"), false)
+	emptyFilter := newContainsFilter([]byte(""), false)
+
+	// notfound OR "" produces TrueFilter
+	orFilter := newOrFilter(notfoundFilter, emptyFilter)
+	require.Equal(t, TrueFilter, orFilter)
+
+	// "(notfound|)" contains an empty branch → TrueFilter
+	regexFilter, err := parseRegexpFilter("(notfound|)", true, false)
+	require.NoError(t, err)
+	require.Equal(t, TrueFilter, regexFilter)
+}
+
 func Benchmark_LineFilter(b *testing.B) {
 	b.ReportAllocs()
 	logline := `level=bar ts=2020-02-22T14:57:59.398312973Z caller=logging.go:44 traceID=2107b6b551458908 msg="GET /buzz (200) 4.599635ms`