diff --git a/include/miniocpp/credentials.h b/include/miniocpp/credentials.h
index bcf0fb6..9c68e8d 100644
--- a/include/miniocpp/credentials.h
+++ b/include/miniocpp/credentials.h
@@ -69,7 +69,7 @@ struct Credentials {
   bool IsExpired() const { return expired(expiration); }
 
   explicit operator bool() const {
-    return !err && !access_key.empty() && expired(expiration);
+    return !err && !access_key.empty() && !expired(expiration);
   }
 
   static Credentials ParseXML(std::string_view data, const std::string& root);