diff --git a/web/api/v1/api.go b/web/api/v1/api.go
index 146265613..06e6cc1dc 100644
--- a/web/api/v1/api.go
+++ b/web/api/v1/api.go
@@ -337,21 +337,25 @@ func (api *API) series(r *http.Request) (interface{}, *apiError) {
 	}
 	defer q.Close()
 
-	// TODO(fabxc): expose merge functionality in storage interface.
-	// We just concatenate results for all sets of matchers, which may produce
-	// duplicated results.
-	metrics := []labels.Labels{}
+	var set storage.SeriesSet
 
 	for _, mset := range matcherSets {
-		series := q.Select(mset...)
-		for series.Next() {
-			metrics = append(metrics, series.At().Labels())
-		}
-		if series.Err() != nil {
-			return nil, &apiError{errorExec, series.Err()}
+		if set == nil {
+			set = q.Select(mset...)
+		} else {
+			set = storage.DeduplicateSeriesSet(set, q.Select(mset...))
 		}
 	}
 
+	metrics := []labels.Labels{}
+
+	for set.Next() {
+		metrics = append(metrics, set.At().Labels())
+	}
+	if set.Err() != nil {
+		return nil, &apiError{errorExec, set.Err()}
+	}
+
 	return metrics, nil
 }
 
diff --git a/web/api/v1/api_test.go b/web/api/v1/api_test.go
index b9590dd6f..19aa9ca02 100644
--- a/web/api/v1/api_test.go
+++ b/web/api/v1/api_test.go
@@ -310,7 +310,6 @@ func TestEndpoints(t *testing.T) {
 			},
 			response: []labels.Labels{
 				labels.FromStrings("__name__", "test_metric1", "foo", "boo"),
-				labels.FromStrings("__name__", "test_metric1", "foo", "boo"), // TODO(fabxc): see comment in implementation.
 			},
 		},
 		{