diff --git a/bin/executable_showcert b/bin/executable_showcert
index 3ecb4bd..88d7841 100644
--- a/bin/executable_showcert
+++ b/bin/executable_showcert
@@ -2,6 +2,8 @@
 
 [[ -z $1 ]] && { echo "where to get the cert?" >&2; exit 1; }
 
+PORT=${2:-443}
+
 fetch() {
     if [[ $1 == "-" ]]
     then
@@ -15,7 +17,7 @@ fetch() {
 }
 
 fetch_remote() {
-    : | openssl s_client -connect $1:443 2>/dev/null| awk '/BEGIN CERTIFICATE/,/END CERTIFICATE/'
+    : | openssl s_client -connect $1:${PORT} 2>/dev/null| awk '/BEGIN CERTIFICATE/,/END CERTIFICATE/'
 }
 
 fetch_file() {