diff --git a/README.md b/README.md
index d3862dd..f98c6d8 100644
--- a/README.md
+++ b/README.md
@@ -34,10 +34,12 @@ check_synology --help
 
 ```shell
 check_synology
-usage: check_synology [-h] [-w W] [-c C] [-t T] [-r R] [-p PORT] hostname username authkey privkey {load,memory,disk,storage,update,status}
+
+usage: check_synology [-h] [-w W] [-c C] [-t T] [-r R] [-p PORT] [-e PROTOCOL] hostname username authkey privkey {load,memory,disk,storage,update,status}
 ```
 
 A custom port can be specified by using `-p`. The default value is `161`.
+A custom privacy protocol can be specified by using `-e`. The default value is `AES128`.
 Custom timeouts (`-t`) and retries (`-r`) can be specified by using `-t` and `-r` respectively. The default values are `-t 10` and `-r 3`.
 
 ### Available modes
diff --git a/check_synology.py b/check_synology.py
index 3c8c093..6591dc6 100755
--- a/check_synology.py
+++ b/check_synology.py
@@ -19,6 +19,7 @@
 parser.add_argument("-w", help="warning value for selected mode", type=int)
 parser.add_argument("-c", help="critical value for selected mode", type=int)
 parser.add_argument("-p", help="the snmp port", type=int, dest="port", default=161)
+parser.add_argument("-e", help="SNMP privacy protocol encryption", type=str, default="AES128", choices=["AES128", "DES"])
 parser.add_argument("-t", help="timeout for snmp connection", type=int, default=10)
 parser.add_argument("-r", help="retries for snmp connection if timeout occurs", type=int, default=3)
 args = parser.parse_args()
@@ -31,6 +32,7 @@
 mode = args.mode
 warning = args.w
 critical = args.c
+priv_protocol = args.e
 snmp_timeout = args.t
 snmp_retries = args.r
 
@@ -57,7 +59,7 @@ def croak(message=None):
         auth_password=auth_key,
         auth_protocol="MD5",
         privacy_password=priv_key,
-        privacy_protocol="AES128")
+        privacy_protocol=priv_protocol)
 
 except Exception as e:
     croak(e)