diff --git a/trie/slimtrie.go b/trie/slimtrie.go
index daa78111..db8b5b40 100644
--- a/trie/slimtrie.go
+++ b/trie/slimtrie.go
@@ -122,7 +122,7 @@ func newSlimTrie(e encode.Encoder, keys []string, values interface{}) (*SlimTrie
 	leavesi := make([]int32, 0, n)
 	leavesv := make([]interface{}, 0, n)
 
-	queue := make([]subset, 0, n)
+	queue := make([]subset, 0, n*2)
 	queue = append(queue, subset{0, n, 0})
 
 	for i := 0; i < len(queue); i++ {
@@ -177,7 +177,7 @@ func newSlimTrie(e encode.Encoder, keys []string, values interface{}) (*SlimTrie
 
 				// Continue looking for the first key not starting with label
 				var j int
-				for j = s; j < e; j++ {
+				for j = s + 1; j < e; j++ {
 					word := bw4.Get(keys[j], prefI)
 					if word != label {
 						break