diff --git a/example-dns-01-nsupdate-script.md b/example-dns-01-nsupdate-script.md
index 40cd638..bfe9975 100644
--- a/example-dns-01-nsupdate-script.md
+++ b/example-dns-01-nsupdate-script.md
@@ -14,30 +14,24 @@ This hook script uses the nsupdate utility from the bind package to solve dns-01
 set -e
 set -u
 set -o pipefail
-umask 077
 
 NSUPDATE="nsupdate -k /path/to/Kdnsupdatekey.private"
-done="no"
 
-if [[ "$1" = "deploy_challenge" ]]; then
-    printf "update add _acme-challenge.%s. 300 in TXT \"%s\"\n\n" "${2}" "${4}" | $NSUPDATE
-    done="yes"
-fi
-
-if [[ "$1" = "clean_challenge" ]]; then
-    printf "update delete _acme-challenge.%s. 300 in TXT \"%s\"\n\n" "${2}" "${4}" | $NSUPDATE
-    done="yes"
-fi
-
-if [[ "${1}" = "deploy_cert" ]]; then
-    # do nothing for now
-    done="yes"
-fi
-
-if [[ ! "${done}" = "yes" ]]; then
-    echo Unkown hook "${1}"
-    exit 1
-fi
+case "$1" in
+    "deploy_challenge")
+        printf "update add _acme-challenge.%s. 300 in TXT \"%s\"\n\n" "${2}" "${4}" | $NSUPDATE
+        ;;
+    "clean_challenge")
+        printf "update delete _acme-challenge.%s. 300 in TXT \"%s\"\n\n" "${2}" "${4}" | $NSUPDATE
+        ;;
+    "deploy_cert")
+        # do nothing for now
+        ;;
+    *)
+        echo Unkown hook "${1}"
+        exit 1
+        ;;
+esac
 
 exit 0
 ```
\ No newline at end of file