--- a/browser/base/content/browser.js
+++ b/browser/base/content/browser.js
@@ -704,17 +704,17 @@ function gKeywordURIFixup({ target: brow
   // decimal representations of IPs are normalized to a 'regular'
   // dot-separated IP address by network code, but that only happens for
   // numbers that don't overflow. Longer numbers do not get normalized,
   // but still work to access IP addresses. So for instance,
   // 1097347366913 (ff7f000001) gets resolved by using the final bytes,
   // making it the same as 7f000001, which is 127.0.0.1 aka localhost.
   // While 2130706433 would get normalized by network, 1097347366913
   // does not, and we have to deal with both cases here:
-  if (isIPv4Address(asciiHost) || /^\d+$/.test(asciiHost))
+  if (isIPv4Address(asciiHost) || /^(?:\d+|0x[a-f0-9]+)$/i.test(asciiHost))
     return;
 
   let onLookupComplete = (request, record, status) => {
     let browser = weakBrowser.get();
     if (!Components.isSuccessCode(status) || !browser)
       return;
 
     let currentURI = browser.currentURI;

--- a/browser/base/content/test/urlbar/browser_urlbarSearchSingleWordNotification.js
+++ b/browser/base/content/test/urlbar/browser_urlbarSearchSingleWordNotification.js
@@ -98,16 +98,39 @@ add_task(function* test_navigate_large_n
   yield BrowserTestUtils.browserLoaded(tab.linkedBrowser);
   yield* runURLBarSearchTest({
     valueToOpen: "123456789012345",
     expectSearch: true,
     expectNotification: false
   });
   gBrowser.removeTab(tab);
 });
+
+add_task(function* test_navigate_small_hex_number() {
+  let tab = gBrowser.selectedTab = gBrowser.addTab("about:blank");
+  yield BrowserTestUtils.browserLoaded(tab.linkedBrowser);
+  yield* runURLBarSearchTest({
+    valueToOpen: "0x1f00ffff",
+    expectSearch: true,
+    expectNotification: false
+  });
+  gBrowser.removeTab(tab);
+});
+
+add_task(function* test_navigate_large_hex_number() {
+  let tab = gBrowser.selectedTab = gBrowser.addTab("about:blank");
+  yield BrowserTestUtils.browserLoaded(tab.linkedBrowser);
+  yield* runURLBarSearchTest({
+    valueToOpen: "0x7f0000017f000001",
+    expectSearch: true,
+    expectNotification: false
+  });
+  gBrowser.removeTab(tab);
+});
+
 function get_test_function_for_localhost_with_hostname(hostName, isPrivate) {
   return function* test_navigate_single_host() {
     const pref = "browser.fixup.domainwhitelist.localhost";
     let win;
     if (isPrivate) {
       win = yield promiseOpenAndLoadWindow({private: true}, true);
       let deferredOpenFocus = Promise.defer();
       waitForFocus(deferredOpenFocus.resolve, win);