diff --git a/src/apps/fido_u2f/__init__.py b/src/apps/fido_u2f/__init__.py
index 013e7b47d..e691a8599 100644
--- a/src/apps/fido_u2f/__init__.py
+++ b/src/apps/fido_u2f/__init__.py
@@ -435,7 +435,7 @@ class ConfirmContent(ui.Widget):
             header = 'U2F Authenticate'
         ui.header(header, ui.ICON_DEFAULT, ui.GREEN, ui.BG, ui.GREEN)
         ui.display.image((ui.WIDTH - 64) // 2, 64, self.app_icon)
-        ui.display.text_center(ui.WIDTH // 2, 176, self.app_name, ui.MONO, ui.FG, ui.BG)
+        ui.display.text_center(ui.WIDTH // 2, 168, self.app_name, ui.MONO, ui.FG, ui.BG)
 
 
 _CONFIRM_STATE_TIMEOUT_MS = const(10 * 1000)
@@ -472,10 +472,21 @@ class ConfirmState:
     @ui.layout
     async def confirm_layout(self) -> None:
         from trezor.ui.confirm import HoldToConfirmDialog, CONFIRMED
+        from trezor.ui.text import Text
+
+        if bytes(self.app_id) == _BOGUS_APPID:
+            text = Text(
+                'U2F mismatch', ui.ICON_WRONG,
+                'Another U2F device',
+                'was used to register',
+                'in this application.',
+                icon_color=ui.RED)
+            text.render()
+            await loop.sleep(3 * 1000 * 1000)
+            return True
 
         content = ConfirmContent(self.action, self.app_id)
         dialog = HoldToConfirmDialog(content)
-
         return await dialog == CONFIRMED