diff --git a/packages/firebase_dart/lib/src/auth/error.dart b/packages/firebase_dart/lib/src/auth/error.dart
index aa6e709..6c8bed0 100644
--- a/packages/firebase_dart/lib/src/auth/error.dart
+++ b/packages/firebase_dart/lib/src/auth/error.dart
@@ -400,7 +400,7 @@ class FirebaseAuthException extends FirebaseException {
       credential.hashCode;
 
   @override
-  bool operator ==(other) =>
+  bool operator ==(covariant FirebaseException other) =>
       other is FirebaseAuthException &&
       other.code == code &&
       other.message == message &&