diff --git a/lib/dict.js b/lib/dict.js
index 7713e5d..39f571d 100644
--- a/lib/dict.js
+++ b/lib/dict.js
@@ -3,7 +3,7 @@ var LEFT = 0;
 var RIGHT = 1;
 var path = require("path");
 var glob = require("glob");
-
+var createPrefixTree = require("./prefixtree").createPrefixTree;
 var WordcutDict = {
 
 
@@ -41,6 +41,7 @@ var WordcutDict = {
 
   finalizeDict: function(){
     this.dict = this.sortuniq(this.dict);
+    this.tree = createPrefixTree(this.dict.map(w => [w, null]))
   },
 
   addFiles: function(files, finalize){
@@ -93,38 +94,31 @@ var WordcutDict = {
   },
 
   createAcceptor: function () {
+    let dict = this;
     return {
-      l: 0,
-      r: this.dict.length - 1,
+      nodeId: 0,
       strOffset: 0,
       isFinal: false,
-      dict: this,
-      transit: function (ch) {
-        return this.dict.transit(this, ch);
-      },
       isError: false,
       tag: "DICT",
       w: 1,
-      type: "DICT"
+      type: "DICT",
+      dict: dict,
+
+      transit(ch) {
+	return this.dict.transit(this, ch)
+      }
     };
   },
 
   transit: function (acceptor, ch) {
-    var l = this.dictSeek(acceptor.l,
-      acceptor.r,
-      ch,
-      acceptor.strOffset,
-      LEFT);
-    if (l !== null) {
-      var r = this.dictSeek(l,
-        acceptor.r,
-        ch,
-        acceptor.strOffset,
-        RIGHT);
-      acceptor.l = l;
-      acceptor.r = r;
-      acceptor.strOffset++;
-      acceptor.isFinal = this.isFinal(acceptor);
+    let child = this.tree.lookup(acceptor.nodeId, acceptor.strOffset, ch)
+    if (child !== null) {
+
+      let [nodeId, isFinal, payload] = child
+      acceptor.nodeId = nodeId
+      acceptor.strOffset++
+      acceptor.isFinal = isFinal
     } else {
       acceptor.isError = true;
     }
diff --git a/test/tests.js b/test/tests.js
index 4a36772..1370aa5 100644
--- a/test/tests.js
+++ b/test/tests.js
@@ -133,5 +133,4 @@ describe("Wordcut", function() {
     expect(segmentedResult).to.deep.equal(["ฉัน","ชอบ","กิน","ข้าว"])
   });
 
-
 });