diff --git a/src/Http/Controllers/CP/Users/RolesController.php b/src/Http/Controllers/CP/Users/RolesController.php
index 80fa2da285d..25ba6eddccb 100644
--- a/src/Http/Controllers/CP/Users/RolesController.php
+++ b/src/Http/Controllers/CP/Users/RolesController.php
@@ -155,8 +155,8 @@ public function update(Request $request, $role)
 
         if ($request->super && User::current()->isSuper()) {
             $role->permissions(['super']);
-        } elseif (! in_array('super', $request->permissions ?? [])) {
-            $role->permissions($request->permissions);
+        } elseif ($request->has('permissions') && ! in_array('super', $request->permissions)) {
+            $role->permissions($this->preserveUnregisteredPermissions($role, $request->permissions));
         }
 
         $role->save();
@@ -179,6 +179,17 @@ public function destroy($role)
         return response('', 204);
     }
 
+    private function preserveUnregisteredPermissions($role, $permissions)
+    {
+        $registered = Permission::boot()->flattened()->map->value();
+
+        $unregistered = $role->permissions()
+            ->diff($registered)
+            ->reject(fn ($permission) => $permission === 'super');
+
+        return collect($permissions)->merge($unregistered)->unique()->values()->all();
+    }
+
     protected function updateTree($tree, $role = null)
     {
         return $tree->map(function ($group) use ($role) {
diff --git a/tests/Feature/Roles/UpdateRoleTest.php b/tests/Feature/Roles/UpdateRoleTest.php
index f0da48eae5f..8355d745497 100644
--- a/tests/Feature/Roles/UpdateRoleTest.php
+++ b/tests/Feature/Roles/UpdateRoleTest.php
@@ -78,7 +78,7 @@ public function it_updates_a_role()
         $role = tap(
             Role::make('test')
                 ->title('Test')
-                ->permissions(['one', 'two'])
+                ->permissions(['configure fields', 'manage preferences'])
         )->save();
 
         $this
@@ -87,7 +87,7 @@ public function it_updates_a_role()
             ->update($role, [
                 'title' => 'Updated',
                 'handle' => 'changed',
-                'permissions' => ['one', 'three'],
+                'permissions' => ['configure fields', 'resolve duplicate ids'],
             ])
             ->assertOk()
             ->assertJson(['redirect' => cp_route('roles.index')]);
@@ -95,7 +95,53 @@ public function it_updates_a_role()
         $this->assertNull(Role::find('test'));
         $role = Role::find('changed');
         $this->assertEquals('Updated', $role->title());
-        $this->assertEquals(['one', 'three'], $role->permissions()->all());
+        $this->assertEquals(['configure fields', 'resolve duplicate ids'], $role->permissions()->all());
+        $this->assertFalse($role->isSuper());
+    }
+
+    #[Test]
+    public function it_preserves_permissions_that_are_no_longer_registered()
+    {
+        // A permission that used to be registered, but no longer is. For example, one
+        // belonging to an addon that's been disabled, or a deprecated core permission.
+        $role = tap(
+            Role::make('test')
+                ->title('Test')
+                ->permissions(['configure fields', 'manage preferences', 'do addon things'])
+        )->save();
+
+        $this
+            ->actingAsUserWithPermissions(['edit roles'])
+            ->withActiveElevatedSession()
+            ->update($role, [
+                'permissions' => ['configure fields'],
+            ])
+            ->assertOk();
+
+        $role = Role::find('test');
+        $this->assertEquals(['configure fields', 'do addon things'], $role->permissions()->all());
+    }
+
+    #[Test]
+    public function demoting_a_super_role_does_not_resurrect_the_super_permission()
+    {
+        $role = tap(
+            Role::make('test')
+                ->title('Test')
+                ->permissions(['super'])
+        )->save();
+
+        $this
+            ->actingAs(tap(User::make()->makeSuper())->save())
+            ->withActiveElevatedSession()
+            ->update($role, [
+                'super' => false,
+                'permissions' => [],
+            ])
+            ->assertOk();
+
+        $role = Role::find('test');
+        $this->assertEquals([], $role->permissions()->all());
         $this->assertFalse($role->isSuper());
     }