diff --git a/lib/impure/ssl.nim b/lib/impure/ssl.nim
index e7c83e5c28..5a39f6f31e 100644
--- a/lib/impure/ssl.nim
+++ b/lib/impure/ssl.nim
@@ -13,7 +13,7 @@
 import openssl, strutils, os
 
 type
-  TSecureSocket* = object
+  TSecureSocket* = object {.final.}
     ssl: PSSL
     bio: PBIO
 
diff --git a/lib/pure/smtp.nim b/lib/pure/smtp.nim
index dd270cee2e..00e636ebc8 100644
--- a/lib/pure/smtp.nim
+++ b/lib/pure/smtp.nim
@@ -27,13 +27,13 @@
 import sockets, strutils, strtabs, ssl, base64
 
 type
-  TSMTP* = object
+  TSMTP* = object {.final.}
     sock: TSocket
     sslSock: TSecureSocket
     ssl: Bool
     debug: Bool
   
-  TMessage* = object
+  TMessage* = object {.final.}
     msgTo: seq[String]
     msgCc: seq[String]
     msgSubject: String