diff --git a/lib/script/script.js b/lib/script/script.js
index eded4d1..1489920 100644
--- a/lib/script/script.js
+++ b/lib/script/script.js
@@ -36,15 +36,17 @@ var Script = function Script(from) {
     return Script.fromAddress(from);
   } else if (from instanceof Script) {
     return Script.fromBuffer(from.toBuffer());
-  } else if (typeof from === 'string') {
+  } else if (_.isString(from)) {
     return Script.fromString(from);
-  } else if (typeof from !== 'undefined') {
+  } else if (_.isObject(from) && _.isArray(from.chunks)) {
     this.set(from);
   }
 };
 
 Script.prototype.set = function(obj) {
-  this.chunks = obj.chunks || this.chunks;
+  $.checkArgument(_.isObject(obj));
+  $.checkArgument(_.isArray(obj.chunks));
+  this.chunks = obj.chunks;
   return this;
 };
 
diff --git a/test/script/script.js b/test/script/script.js
index 4430ce2..8b3924e 100644
--- a/test/script/script.js
+++ b/test/script/script.js
@@ -15,7 +15,35 @@ describe('Script', function() {
 
   it('should make a new script', function() {
     var script = new Script();
-    should.exist(script);
+    expect(script).to.be.instanceof(Script);
+    expect(script.chunks).to.deep.equal([]);
+  });
+
+  it('should make a new script when from is null', function() {
+    var script = new Script(null);
+    expect(script).to.be.instanceof(Script);
+    expect(script.chunks).to.deep.equal([]);
+  });
+
+  describe('#set', function() {
+    var script = new Script();
+
+    it('should be object', function() {
+      expect(function() {
+        script.set(null);
+      }).to.throw(/^Invalid Argument$/)
+    });
+
+    it('chunks should be array', function() {
+      expect(function() {
+        script.set({chunks: 1});
+      }).to.throw(/^Invalid Argument$/);
+    });
+
+    it('set chunks', function() {
+      script.set({chunks: [1]});
+      expect(script.chunks).to.deep.equal([1]);
+    });
   });
 
   describe('#fromBuffer', function() {