diff --git a/pkg/store/proxy.go b/pkg/store/proxy.go
index 040859cc368..666f130eceb 100644
--- a/pkg/store/proxy.go
+++ b/pkg/store/proxy.go
@@ -338,13 +338,12 @@ func (s *ProxyStore) Series(originalRequest *storepb.SeriesRequest, srv storepb.
 			continue
 		}
 
-		matches, matched := s.tsdbSelector.MatchLabelSets(st.LabelSets()...)
+		matches, extraMatchers := s.tsdbSelector.MatchLabelSets(st.LabelSets()...)
 		if !matches {
 			continue
 		}
-		if len(matched) < len(st.LabelSets()) {
-			storeLabelSets = append(storeLabelSets, matched...)
-		}
+		storeLabelSets = append(storeLabelSets, extraMatchers...)
+
 		stores = append(stores, st)
 	}
 	if len(stores) == 0 {
diff --git a/pkg/store/proxy_test.go b/pkg/store/proxy_test.go
index 8a128796d72..97ebfdb55d6 100644
--- a/pkg/store/proxy_test.go
+++ b/pkg/store/proxy_test.go
@@ -1688,7 +1688,7 @@ type rawSeries struct {
 }
 
 func seriesEquals(t *testing.T, expected []rawSeries, got []storepb.Series) {
-	testutil.Equals(t, len(expected), len(got), "got unexpected number of series: \n %v", got)
+	testutil.Equals(t, len(expected), len(got), "got unexpected number of series: \n want: %v \n  got: %v", expected, got)
 
 	ret := make([]rawSeries, len(got))
 	for i, s := range got {
diff --git a/pkg/store/tsdb_selector.go b/pkg/store/tsdb_selector.go
index 5ab1832a639..c9beef6e777 100644
--- a/pkg/store/tsdb_selector.go
+++ b/pkg/store/tsdb_selector.go
@@ -33,10 +33,11 @@ func NewTSDBSelector(relabelConfig []*relabel.Config) *TSDBSelector {
 }
 
 // MatchLabelSets returns true if the given label sets match the TSDBSelector.
-// It also returns those label sets that were matched.
+// As a second parameter, it returns the matched label sets if they are a subset of the given input.
+// Otherwise the second return value is nil.
 func (sr *TSDBSelector) MatchLabelSets(labelSets ...labels.Labels) (bool, []labels.Labels) {
 	if sr.relabelConfig == nil || len(labelSets) == 0 {
-		return true, labelSets
+		return true, nil
 	}
 	matchedLabelSets := sr.runRelabelRules(labelSets)
 	return len(matchedLabelSets) > 0, matchedLabelSets