diff --git a/src/ua-parser.js b/src/ua-parser.js
index cb60dfc..18ac0f6 100755
--- a/src/ua-parser.js
+++ b/src/ua-parser.js
@@ -787,12 +787,17 @@
         this.rgxIs = propIs[1];
     }
     UAItem.prototype.is = function (strCheck) {
+        var is = false;
         for (var i in this.propIs) {
             if (sanitize(this[this.propIs[i]], this.rgxIs) == sanitize(strCheck, this.rgxIs)) {
-                return true;
+                is = true;
+                if (strCheck != UNDEF_TYPE) break;
+            } else if (strCheck == UNDEF_TYPE && is) {
+                is = !is;
+                break;
             }
         }
-        return false;
+        return is;
     };
     UAItem.prototype.toString = function () {
         var str = '';
diff --git a/test/test.js b/test/test.js
index a85e9da..622df97 100644
--- a/test/test.js
+++ b/test/test.js
@@ -205,9 +205,6 @@ describe('is() utility method', function () {
         assert.strictEqual(uap.getDevice().is("mobile"), true);
 
         assert.strictEqual(uap.getResult().device.is("Nokia"), true);
-
-        uap.setUA("Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_6) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/14.0.3 Safari/605.1.15");
-        assert.strictEqual(uap.getDevice().is("undefined"), true);
     });
 
     it('Should get result after reassignment', function () {
@@ -225,7 +222,16 @@ describe('is() utility method', function () {
         assert.strictEqual(uap.getEngine().is("Blink"), true);
     });
 
-    it('Should accept arch equivalent name', function () {
+    it('Should refrain from "undefined" until all properties are checked', function () {
+        assert.strictEqual(uap.getDevice().is("undefined"), false);
+        assert.strictEqual(uap.getDevice().is("Apple"), true);
+
+        uap.setUA("");
+        assert.strictEqual(uap.getDevice().is("undefined"), true);
+    });
+
+    //it('Should accept arch equivalent name', function () {
+    it('Should accept exact arch name', function () {
         uap.setUA("Mozilla/5.0 (X11; Ubuntu; Linux i686; rv:19.0) Gecko/20100101 Firefox/19.0");
         assert.strictEqual(uap.getCPU().architecture, "ia32");
         assert.strictEqual(uap.getCPU().is("ia32"), true);