diff --git a/components/script/dom/navigator.rs b/components/script/dom/navigator.rs
index 257e1d2dfab..0b96e355a2f 100644
--- a/components/script/dom/navigator.rs
+++ b/components/script/dom/navigator.rs
@@ -54,5 +54,9 @@ impl<'a> NavigatorMethods for JSRef<'a, Navigator> {
     fn UserAgent(self) -> DOMString {
         navigatorinfo::UserAgent()
     }
+
+    fn AppVersion(self) -> DOMString {
+        navigatorinfo::AppVersion()
+    }
 }
 
diff --git a/components/script/dom/navigatorinfo.rs b/components/script/dom/navigatorinfo.rs
index 7dc94d85374..d4aec6999ab 100644
--- a/components/script/dom/navigatorinfo.rs
+++ b/components/script/dom/navigatorinfo.rs
@@ -33,3 +33,7 @@ pub fn UserAgent() -> DOMString {
         None => "".to_owned(),
     }
 }
+
+pub fn AppVersion() -> DOMString {
+    "4.0".to_owned()
+}
diff --git a/components/script/dom/webidls/Navigator.webidl b/components/script/dom/webidls/Navigator.webidl
index 0ce509f4c04..67b5cf95018 100644
--- a/components/script/dom/webidls/Navigator.webidl
+++ b/components/script/dom/webidls/Navigator.webidl
@@ -19,7 +19,7 @@ Navigator implements NavigatorID;
 interface NavigatorID {
   readonly attribute DOMString appCodeName; // constant "Mozilla"
   readonly attribute DOMString appName;
-  //readonly attribute DOMString appVersion;
+  readonly attribute DOMString appVersion;
   readonly attribute DOMString platform;
   readonly attribute DOMString product; // constant "Gecko"
   boolean taintEnabled(); // constant false
diff --git a/components/script/dom/workernavigator.rs b/components/script/dom/workernavigator.rs
index 40c74e78b38..ea446f986cb 100644
--- a/components/script/dom/workernavigator.rs
+++ b/components/script/dom/workernavigator.rs
@@ -55,5 +55,9 @@ impl<'a> WorkerNavigatorMethods for JSRef<'a, WorkerNavigator> {
     fn UserAgent(self) -> DOMString {
         navigatorinfo::UserAgent()
     }
+
+    fn AppVersion(self) -> DOMString {
+        navigatorinfo::AppVersion()
+    }
 }
 
diff --git a/tests/content/test_navigator.html b/tests/content/test_navigator.html
index 0b8b048bb2e..72cd17ab8f1 100644
--- a/tests/content/test_navigator.html
+++ b/tests/content/test_navigator.html
@@ -14,6 +14,7 @@ is(nav.taintEnabled(), false);
 is(nav.appName, "Netscape");
 is(nav.appCodeName, "Mozilla");
 is(nav.platform, "");
+is(nav.appVersion, "4.0");
 </script>
 </body>
 </html>
diff --git a/tests/wpt/metadata/html/dom/interfaces.html.ini b/tests/wpt/metadata/html/dom/interfaces.html.ini
index d1d1be10cf3..3102ed874ba 100644
--- a/tests/wpt/metadata/html/dom/interfaces.html.ini
+++ b/tests/wpt/metadata/html/dom/interfaces.html.ini
@@ -8637,9 +8637,6 @@
   [Navigator interface object length]
     expected: FAIL
 
-  [Navigator interface: attribute appVersion]
-    expected: FAIL
-
   [Navigator interface: attribute language]
     expected: FAIL
 
@@ -8682,9 +8679,6 @@
   [Navigator interface: attribute javaEnabled]
     expected: FAIL
 
-  [Navigator interface: window.navigator must inherit property "appVersion" with the proper type (2)]
-    expected: FAIL
-
   [Navigator interface: window.navigator must inherit property "language" with the proper type (7)]
     expected: FAIL
 
@@ -9231,9 +9225,6 @@
   [WorkerNavigator interface object length]
     expected: FAIL
 
-  [WorkerNavigator interface: attribute appVersion]
-    expected: FAIL
-
   [WorkerNavigator interface: attribute language]
     expected: FAIL
 
diff --git a/tests/wpt/metadata/workers/interfaces.worker.js.ini b/tests/wpt/metadata/workers/interfaces.worker.js.ini
index 03f07afd004..97bda445b76 100644
--- a/tests/wpt/metadata/workers/interfaces.worker.js.ini
+++ b/tests/wpt/metadata/workers/interfaces.worker.js.ini
@@ -81,9 +81,6 @@
   [WorkerNavigator interface object length]
     expected: FAIL
 
-  [WorkerNavigator interface: attribute appVersion]
-    expected: FAIL
-
   [WorkerNavigator interface: attribute language]
     expected: FAIL
 
@@ -93,9 +90,6 @@
   [WorkerNavigator interface: attribute onLine]
     expected: FAIL
 
-  [WorkerNavigator interface: self.navigator must inherit property "appVersion" with the proper type (2)]
-    expected: FAIL
-
   [WorkerNavigator interface: self.navigator must inherit property "language" with the proper type (7)]
     expected: FAIL