diff --git a/src/dotnet/src/Mil.Navy.Nrl.Norm/NormSession.cs b/src/dotnet/src/Mil.Navy.Nrl.Norm/NormSession.cs
index c2fc70a..6f24080 100644
--- a/src/dotnet/src/Mil.Navy.Nrl.Norm/NormSession.cs
+++ b/src/dotnet/src/Mil.Navy.Nrl.Norm/NormSession.cs
@@ -1,5 +1,4 @@
-using System.Runtime.CompilerServices;
-using System.Text;
+using System.Text;
 
 namespace Mil.Navy.Nrl.Norm
 {
@@ -75,10 +74,12 @@ namespace Mil.Navy.Nrl.Norm
         /// </summary>
         /// <param name="handle">Specifies the session to return.</param>
         /// <returns>Returns a NormSession.</returns>
-        [MethodImpl(MethodImplOptions.Synchronized)]
         internal static NormSession GetSession(long handle)
         {
-            return _normSessions[handle];
+            lock (_normSessions)
+            {
+                return _normSessions[handle];
+            }
         }
 
         /// <summary>