diff --git a/genkeys.go b/genkeys.go
index 22f29faff..7781c26d9 100644
--- a/genkeys.go
+++ b/genkeys.go
@@ -493,7 +493,7 @@ func (k Key) String() string {
 	{{range $index, $name := .UIKeyNames}}case Key{{$name}}:
 		return {{$name | printf "Key%s" | printf "%q"}}
 	{{end}}}
-	panic(fmt.Sprintf("ui: invalid key: %d", k))
+	return fmt.Sprintf("Key(%d)", k)
 }
 `
 
diff --git a/internal/ui/keys.go b/internal/ui/keys.go
index 99e2bbb21..18fa8352b 100644
--- a/internal/ui/keys.go
+++ b/internal/ui/keys.go
@@ -348,5 +348,5 @@ func (k Key) String() string {
 	case KeyTab:
 		return "KeyTab"
 	}
-	panic(fmt.Sprintf("ui: invalid key: %d", k))
+	return fmt.Sprintf("Key(%d)", k)
 }