diff --git a/imageroot/actions/configure-module/validate-input.json b/imageroot/actions/configure-module/validate-input.json
index 5cac7f5..cdbf9a5 100644
--- a/imageroot/actions/configure-module/validate-input.json
+++ b/imageroot/actions/configure-module/validate-input.json
@@ -22,7 +22,8 @@
         "host": {
             "type": "string",
             "description": "Host name for the application, like 'collabora.nethserver.org'",
-            "format": "idn-hostname"
+            "format": "hostname",
+            "pattern": "\\."
         },
         "lets_encrypt": {
             "type": "boolean",
diff --git a/ui/public/i18n/en/translation.json b/ui/public/i18n/en/translation.json
index 0b088a5..7257a90 100644
--- a/ui/public/i18n/en/translation.json
+++ b/ui/public/i18n/en/translation.json
@@ -38,7 +38,9 @@
     "link": "Admin console",
     "admin_password_string_gte": "The password length must be superior or equal to 8 characters",
     "placeholder_admin_password": "Type a password",
-    "placeholder_collabora_domain": "Type a fully qualified domain name"
+    "placeholder_collabora_domain": "Type a fully qualified domain name",
+    "host_pattern": "Must be a valid fully qualified domain name",
+    "host_format": "Must be a valid fully qualified domain name"
   },
   "about": {
     "title": "About"