diff --git a/model/labels/labels.go b/model/labels/labels.go
index f1226c0b0c..34bb878d18 100644
--- a/model/labels/labels.go
+++ b/model/labels/labels.go
@@ -119,7 +119,7 @@ func (ls *Labels) UnmarshalYAML(unmarshal func(interface{}) error) error {
 func (ls Labels) MatchLabels(on bool, names ...string) Labels {
 	matchedLabels := Labels{}
 
-	nameSet := map[string]struct{}{}
+	nameSet := make(map[string]struct{}, len(names))
 	for _, n := range names {
 		nameSet[n] = struct{}{}
 	}