diff --git a/addon-modules/OpenSim-Modules-Currency/OpenSim.Modules.Currency/NSLCertificateTools.cs b/addon-modules/OpenSim-Modules-Currency/OpenSim.Modules.Currency/NSLCertificateTools.cs
index 886d72b..929ff6f 100644
--- a/addon-modules/OpenSim-Modules-Currency/OpenSim.Modules.Currency/NSLCertificateTools.cs
+++ b/addon-modules/OpenSim-Modules-Currency/OpenSim.Modules.Currency/NSLCertificateTools.cs
@@ -10,6 +10,7 @@ using System.Net.Security;
 using System.Reflection;
 using System.Security.Cryptography.X509Certificates;
 using log4net;
+using Mono.Security;
 #pragma warning restore S1128 // Unused "using" should be removed