--- a/browser/app/profile/firefox.js
+++ b/browser/app/profile/firefox.js
@@ -247,17 +247,17 @@ pref("browser.eme.ui.enabled", false);
 
 // UI tour experience.
 pref("browser.uitour.enabled", true);
 pref("browser.uitour.loglevel", "Error");
 pref("browser.uitour.requireSecure", true);
 pref("browser.uitour.themeOrigin", "https://addons.mozilla.org/%LOCALE%/firefox/themes/");
 pref("browser.uitour.url", "https://www.mozilla.org/%LOCALE%/firefox/%VERSION%/tour/");
 // This is used as a regexp match against the page's URL.
-pref("browser.uitour.readerViewTrigger", "^https:\/\/www\.mozilla\.org\/[^\/]+\/firefox\/reading\/start");
+pref("browser.uitour.readerViewTrigger", "^https:\\/\\/www\\.mozilla\\.org\\/[^\\/]+\\/firefox\\/reading\\/start");
 
 pref("browser.customizemode.tip0.shown", false);
 pref("browser.customizemode.tip0.learnMoreUrl", "https://support.mozilla.org/1/firefox/%VERSION%/%OS%/%LOCALE%/customize");
 
 pref("keyword.enabled", true);
 pref("browser.fixup.domainwhitelist.localhost", true);
 
 pref("general.useragent.locale", "@AB_CD@");