diff --git a/library/ssl_srv.c b/library/ssl_srv.c
index 1841b55..b8c4314 100644
--- a/library/ssl_srv.c
+++ b/library/ssl_srv.c
@@ -2638,8 +2638,7 @@
     if( ext_len > 0 )
     {
         MBEDTLS_PUT_UINT16_BE( ext_len, p, 0 );
-        p += 2;
-        p += ext_len;
+        p += 2 + ext_len;
     }
 
     ssl->out_msglen  = p - buf;