diff --git a/app/vmselect/promql/binary_op.go b/app/vmselect/promql/binary_op.go
index 3bf8ff5648..1c56173bdb 100644
--- a/app/vmselect/promql/binary_op.go
+++ b/app/vmselect/promql/binary_op.go
@@ -257,7 +257,7 @@ func groupJoin(singleTimeseriesSide string, be *metricsql.BinaryOpExpr, rvsLeft,
 			var tsCopy timeseries
 			tsCopy.CopyFromShallowTimestamps(tsLeft)
 			tsCopy.MetricName.SetTags(joinTags, joinPrefix, skipTags, &tsRight.MetricName)
-			bb.B = marshalMetricTagsSorted(bb.B[:0], &tsCopy.MetricName)
+			bb.B = marshalMetricNameSorted(bb.B[:0], &tsCopy.MetricName)
 			pair, ok := m[string(bb.B)]
 			if !ok {
 				m[string(bb.B)] = &tsPair{
@@ -522,7 +522,9 @@ func createTimeseriesMapByTagSet(be *metricsql.BinaryOpExpr, left, right []*time
 		mn := storage.GetMetricName()
 		for _, ts := range arg {
 			mn.CopyFrom(&ts.MetricName)
-			mn.ResetMetricGroup()
+			if !be.KeepMetricNames {
+				mn.ResetMetricGroup()
+			}
 			switch groupOp {
 			case "on":
 				mn.RemoveTagsOn(groupTags)
@@ -531,7 +533,7 @@ func createTimeseriesMapByTagSet(be *metricsql.BinaryOpExpr, left, right []*time
 			default:
 				logger.Panicf("BUG: unexpected binary op modifier %q", groupOp)
 			}
-			bb.B = marshalMetricTagsSorted(bb.B[:0], mn)
+			bb.B = marshalMetricNameSorted(bb.B[:0], mn)
 			k := string(bb.B)
 			m[k] = append(m[k], ts)
 		}
diff --git a/app/vmselect/promql/exec_test.go b/app/vmselect/promql/exec_test.go
index a66f8093d4..a2b2532386 100644
--- a/app/vmselect/promql/exec_test.go
+++ b/app/vmselect/promql/exec_test.go
@@ -3716,7 +3716,7 @@ func TestExecSuccess(t *testing.T) {
 		q := `(
 		  (label_set(time(), "t1", "v1", "__name__", "q1") or label_set(10, "t2", "v2", "__name__", "q2"))
 		    +
-		  (label_set(100, "t1", "v1", "__name__", "q3") or label_set(time(), "t2", "v3"))
+		  (label_set(100, "t1", "v1", "__name__", "q1") or label_set(time(), "t2", "v3"))
 		) keep_metric_names`
 		r := netstorage.Result{
 			MetricName: metricNameExpected,
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index a10f81ab18..1d8a4c7a53 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -28,6 +28,8 @@ The sandbox cluster installation is running under the constant load generated by
 
 ## tip
 
+* BUGFIX: [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html): properly handle `avg_over_time({some_filter}[d]) keep_metric_names` queries, where [`some_filter`](https://docs.victoriametrics.com/keyconcepts/#filtering) matches multiple time series with multiple names, while `d` is bigger or equal to `3h`. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5556).
+
 ## [v1.97.0](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.97.0)
 
 Released at 2024-01-30