diff --git a/app/modules/mqtt.c b/app/modules/mqtt.c
index 2b6a35b3..c3d7b131 100644
--- a/app/modules/mqtt.c
+++ b/app/modules/mqtt.c
@@ -821,7 +821,8 @@ static sint8 socket_connect(struct espconn *pesp_conn)
 #ifdef CLIENT_SSL_ENABLE
   if(mud->secure)
   {
-    espconn_status = espconn_secure_connect(pesp_conn);
+      espconn_secure_set_size(ESPCONN_CLIENT, 5120); /* set SSL buffer size */
+      espconn_status = espconn_secure_connect(pesp_conn);
   }
   else
 #endif
diff --git a/app/modules/net.c b/app/modules/net.c
index 516ccab9..faab54de 100644
--- a/app/modules/net.c
+++ b/app/modules/net.c
@@ -594,6 +594,7 @@ static void socket_connect(struct espconn *pesp_conn)
   {
 #ifdef CLIENT_SSL_ENABLE
     if(nud->secure){
+      espconn_secure_set_size(ESPCONN_CLIENT, 5120); /* set SSL buffer size */
       espconn_secure_connect(pesp_conn);
     }
     else