diff --git a/components/script/dom/htmlinputelement.rs b/components/script/dom/htmlinputelement.rs
index d8acc2dbe75..35e2a6f5116 100644
--- a/components/script/dom/htmlinputelement.rs
+++ b/components/script/dom/htmlinputelement.rs
@@ -33,6 +33,7 @@ use dom::validation::Validatable;
 use dom::virtualmethods::VirtualMethods;
 use ipc_channel::ipc::{self, IpcSender};
 use mime_guess;
+use msg::constellation_msg::Key;
 use net_traits::IpcSend;
 use net_traits::filemanager_thread::{FileManagerThreadMsg, FilterPattern};
 use script_traits::ScriptMsg as ConstellationMsg;
@@ -1046,10 +1047,18 @@ impl VirtualMethods for HTMLInputElement {
                     let action = self.textinput.borrow_mut().handle_keydown(keyevent);
                     match action {
                         TriggerDefaultAction => {
-                            self.implicit_submission(keyevent.CtrlKey(),
-                                                     keyevent.ShiftKey(),
-                                                     keyevent.AltKey(),
-                                                     keyevent.MetaKey());
+                            if let Some(key) = keyevent.get_key() {
+                                match key {
+                                    Key::Enter | Key::KpEnter =>
+                                        self.implicit_submission(keyevent.CtrlKey(),
+                                                                 keyevent.ShiftKey(),
+                                                                 keyevent.AltKey(),
+                                                                 keyevent.MetaKey()),
+                                    // Issue #12071: Tab should not submit forms
+                                    // TODO(3982): Implement form keyboard navigation
+                                    _ => (),
+                                }
+                            };
                         },
                         DispatchInput => {
                             self.value_changed.set(true);
diff --git a/tests/wpt/mozilla/meta/MANIFEST.json b/tests/wpt/mozilla/meta/MANIFEST.json
index 94676a48fdc..eb95a9e286b 100644
--- a/tests/wpt/mozilla/meta/MANIFEST.json
+++ b/tests/wpt/mozilla/meta/MANIFEST.json
@@ -6480,6 +6480,12 @@
             "url": "/_mozilla/mozilla/form_submit_about.html"
           }
         ],
+        "mozilla/form_tab_keyevent.html": [
+          {
+            "path": "mozilla/form_tab_keyevent.html",
+            "url": "/_mozilla/mozilla/form_tab_keyevent.html"
+          }
+        ],
         "mozilla/getBoundingClientRect.html": [
           {
             "path": "mozilla/getBoundingClientRect.html",
diff --git a/tests/wpt/mozilla/tests/mozilla/form_tab_keyevent.html b/tests/wpt/mozilla/tests/mozilla/form_tab_keyevent.html
new file mode 100644
index 00000000000..d909254cb06
--- /dev/null
+++ b/tests/wpt/mozilla/tests/mozilla/form_tab_keyevent.html
@@ -0,0 +1,27 @@
+<!doctype html>
+<meta charset="utf-8">
+<html>
+    <body>
+        <title>Test for issue #12071</title>
+        <script src="/resources/testharness.js"></script>
+        <script src="/resources/testharnessreport.js"></script>
+        <form name="f" id="f">
+            <input type="text" name="input1" id="input1"/>
+            <input type="submit" value="Submit"/>
+        </form>
+        <script>
+            var test = async_test("TabShouldNotSubmit");
+            var form = document.getElementById('f');
+            var form_submitted = false;
+            form.onsubmit = function(e) { form_submitted = true; return false; };
+            document.addEventListener("DOMContentLoaded", function() {
+                test.step(function() {
+                    var input = document.getElementById('input1');
+                    var evt = new KeyboardEvent("keydown", {key : "Tab"});
+                    input.dispatchEvent(evt);
+                });
+            });
+            test.step_timeout(function() { assert_false(form_submitted, "Form should not be submitted"); test.done(); }, 500);
+        </script>
+    </body>
+</html>
