diff --git a/kyaml/yaml/datamap.go b/kyaml/yaml/datamap.go
index f4b7e6664e..c70a19fbd5 100644
--- a/kyaml/yaml/datamap.go
+++ b/kyaml/yaml/datamap.go
@@ -13,11 +13,9 @@ import (
 // SortedMapKeys returns a sorted slice of keys to the given map.
 // Writing this function never gets old.
 func SortedMapKeys(m map[string]string) []string {
-	keys := make([]string, len(m))
-	i := 0
+	keys := make([]string, 0, len(m))
 	for k := range m {
-		keys[i] = k
-		i++
+		keys = append(keys, k)
 	}
 	sort.Strings(keys)
 	return keys