diff --git a/library/ssl_tls.c b/library/ssl_tls.c
index f701a8a..4e7cac7 100644
--- a/library/ssl_tls.c
+++ b/library/ssl_tls.c
@@ -3141,6 +3141,16 @@
     return( 0 );
 }
 
+int ssl_set_truncated_hmac( ssl_context *ssl )
+{
+    if( ssl->endpoint != SSL_IS_CLIENT )
+        return( POLARSSL_ERR_SSL_BAD_INPUT_DATA );
+
+    ssl->trunc_hmac = SSL_TRUNC_HMAC_ENABLED;
+
+    return( 0 );
+}
+
 void ssl_set_renegotiation( ssl_context *ssl, int renegotiation )
 {
     ssl->disable_renegotiation = renegotiation;