--- a/browser/components/nsBrowserGlue.js
+++ b/browser/components/nsBrowserGlue.js
@@ -1707,17 +1707,17 @@ BrowserGlue.prototype = {
         return;
       this._openPreferences("sync", { origin: "doorhanger" });
     }
     this.AlertsService.showAlertNotification(null, title, body, true, null, clickCallback);
   },
 
   // eslint-disable-next-line complexity
   _migrateUI: function BG__migrateUI() {
-    const UI_VERSION = 52;
+    const UI_VERSION = 53;
     const BROWSER_DOCURL = "chrome://browser/content/browser.xul";
 
     let currentUIVersion;
     if (Services.prefs.prefHasUserValue("browser.migration.version")) {
       currentUIVersion = Services.prefs.getIntPref("browser.migration.version");
     } else {
       // This is a new profile, nothing to migrate.
       Services.prefs.setIntPref("browser.migration.version", UI_VERSION);
@@ -2085,16 +2085,29 @@ BrowserGlue.prototype = {
     if (currentUIVersion < 52) {
       // Keep old devtools log persistence behavior after splitting netmonitor and
       // webconsole prefs (bug 1307881).
       if (Services.prefs.getBoolPref("devtools.webconsole.persistlog", false)) {
         Services.prefs.setBoolPref("devtools.netmonitor.persistlog", true);
       }
     }
 
+    // Update user customizations that will interfere with the Safe Browsing V2
+    // to V4 migration (bug 1395419).
+    if (currentUIVersion < 53) {
+      const MALWARE_PREF = "urlclassifier.malwareTable";
+      if (Services.prefs.prefHasUserValue(MALWARE_PREF)) {
+        let malwareList = Services.prefs.getCharPref(MALWARE_PREF);
+        if (malwareList.indexOf("goog-malware-shavar") != -1) {
+          malwareList.replace("goog-malware-shavar", "goog-malware-proto");
+          Services.prefs.setCharPref(MALWARE_PREF, malwareList);
+        }
+      }
+    }
+
     // Update the migration version.
     Services.prefs.setIntPref("browser.migration.version", UI_VERSION);
   },
 
   _checkForDefaultBrowser() {
     // Perform default browser checking.
     if (!ShellService) {
       return;