--- a/toolkit/components/extensions/Extension.jsm
+++ b/toolkit/components/extensions/Extension.jsm
@@ -482,23 +482,19 @@ this.ExtensionData = class {
     result.permissions = [...this.permissions]
       .filter(p => !result.origins.includes(p) && !EXP_PATTERN.test(p));
     return result;
   }
 
   // Compute the difference between two sets of permissions, suitable
   // for presenting to the user.
   static comparePermissions(oldPermissions, newPermissions) {
-    // See bug 1331769: should we do something more complicated to
-    // compare host permissions?
-    // e.g., if we go from <all_urls> to a specific host or from
-    // a *.domain.com to specific-host.domain.com that's actually a
-    // drop in permissions but the simple test below will cause a prompt.
+    let oldMatcher = new MatchPatternSet(oldPermissions.origins);
     return {
-      origins: newPermissions.origins.filter(perm => !oldPermissions.origins.includes(perm)),
+      origins: newPermissions.origins.filter(perm => !oldMatcher.subsumes(new MatchPattern(perm))),
       permissions: newPermissions.permissions.filter(perm => !oldPermissions.permissions.includes(perm)),
     };
   }
 
   async parseManifest() {
     let [manifest] = await Promise.all([
       this.readJSON("manifest.json"),
       Management.lazyInit(),