diff --git a/DearFTP/Connection/Commands/ProtectionCommand.cs b/DearFTP/Connection/Commands/ProtectionCommand.cs
index c7585de..b141392 100644
--- a/DearFTP/Connection/Commands/ProtectionCommand.cs
+++ b/DearFTP/Connection/Commands/ProtectionCommand.cs
@@ -9,14 +9,22 @@
 
         public void Execute(Session session, FtpStream stream, string alias, string argument)
         {
+            var dataConnection = session.DataConnection;
+
             switch (argument.ToUpper())
             {
                 case "C":
-                    session.DataConnection.DesactivateTls();
+                    if (dataConnection.IsTlsProtected)
+                    {
+                        session.DataConnection.DesactivateTls();
+                    }
                     stream.Send(ResponseCode.OK, "Data protection cleared.");
                     break;
                 case "P":
-                    session.DataConnection.ActivateTls();
+                    if (!dataConnection.IsTlsProtected)
+                    {
+                        session.DataConnection.ActivateTls();
+                    }
                     stream.Send(ResponseCode.OK, "Data protection set.");
                     break;
                 default: