diff --git a/auth-new/errors.go b/auth-new/errors.go
index a68efb2..b655563 100644
--- a/auth-new/errors.go
+++ b/auth-new/errors.go
@@ -21,6 +21,11 @@ var (
 	// The given totp token was recently (90 seconds) used for that username
 	// For security reasons, this case will be caught and blocked
 	ErrTotpRecentlyUsed = errors.New("totp token was used too recently")
+	// The stored data for a passkey registration wasn't formatted correctly
+	// and thus can't be used
+	ErrInvalidPasskeyRegistrationData = errors.New(
+		"stored passkey registration data was formatted badly",
+	)
 )
 
 // Helper error type to combine two errors into one