diff --git a/DotNetCasClient/CasAuthentication.cs b/DotNetCasClient/CasAuthentication.cs
index f865d9a..67273ec 100644
--- a/DotNetCasClient/CasAuthentication.cs
+++ b/DotNetCasClient/CasAuthentication.cs
@@ -60,7 +60,7 @@ public sealed class CasAuthentication
 
         // Thread-safe initialization
         private static readonly object LockObject;
-        private static bool initialized;
+        private static volatile bool initialized;
 
         // System.Web/Authentication and System.Web/Authentication/Forms static classes
         internal static AuthenticationSection AuthenticationConfig;