--- a/extensions/auth/nsHttpNegotiateAuth.cpp
+++ b/extensions/auth/nsHttpNegotiateAuth.cpp
@@ -316,17 +316,17 @@ NS_IMPL_ISUPPORTS(GetNextTokenCompleteEv
 //
 // GetNextTokenRunnable
 //
 // This runnable is created by GenerateCredentialsAsync and it runs
 // in nsHttpNegotiateAuth::mNegotiateThread and calling GenerateCredentials.
 //
 class GetNextTokenRunnable final : public mozilla::Runnable
 {
-    virtual ~GetNextTokenRunnable() = default;
+    ~GetNextTokenRunnable() override = default;
     public:
         GetNextTokenRunnable(nsIHttpAuthenticableChannel *authChannel,
                              const char *challenge,
                              bool isProxyAuth,
                              const char16_t *domain,
                              const char16_t *username,
                              const char16_t *password,
                              nsISupports *sessionState,