diff --git a/conf/post_decalrations.conf b/conf/post_decalrations.conf
index 26d889e..37c473d 100644
--- a/conf/post_decalrations.conf
+++ b/conf/post_decalrations.conf
@@ -861,11 +861,11 @@ done
 # ---
 if $allow_ntp_request_out ; then
 
-   if containsElement "${standard_ntp_udp_port}" "${out_udp_port_arr[@]}" ; then
+   if ! containsElement "${standard_ntp_udp_port}" "${out_udp_port_arr[@]}" ; then
       out_udp_port_arr+=("$standard_ntp_udp_port")
    fi
 
-   if containsElement "${standard_ntp_tcp_port}" "${out_tcp_port_arr[@]}" ; then
+   if ! containsElement "${standard_ntp_tcp_port}" "${out_tcp_port_arr[@]}" ; then
       out_tcp_port_arr+=("$standard_ntp_tcp_port")
    fi