diff --git a/webapp/components/utils/UniqueSlugForm.js b/webapp/components/utils/UniqueSlugForm.js
index 935ef8f7e..c254904d0 100644
--- a/webapp/components/utils/UniqueSlugForm.js
+++ b/webapp/components/utils/UniqueSlugForm.js
@@ -5,6 +5,7 @@ export default function UniqueSlugForm({ translate, apollo, currentUser }) {
   return {
     formSchema: {
       slug: [
+        {type: "string", required: true, pattern: /^[a-z0-9_-]+$/, message: translate('settings.validation.slug.regex') },
         {
           asyncValidator(rule, value, callback) {
             debounce(() => {
diff --git a/webapp/locales/de.json b/webapp/locales/de.json
index 496d3f21b..a784cd5f7 100644
--- a/webapp/locales/de.json
+++ b/webapp/locales/de.json
@@ -159,6 +159,7 @@
     },
     "validation": {
       "slug": {
+        "regex": "Es sind nur Kleinbuchstaben, Zahlen, Unterstriche oder Bindestriche erlaubt.",
         "alreadyTaken": "Dieser Benutzername ist schon vergeben."
       }
     },
diff --git a/webapp/locales/en.json b/webapp/locales/en.json
index 660a2b1ee..502aedd67 100644
--- a/webapp/locales/en.json
+++ b/webapp/locales/en.json
@@ -160,6 +160,7 @@
     },
     "validation": {
       "slug": {
+        "regex": "Allowed characters are only lowercase letters, numbers, underscores and hyphens.",
         "alreadyTaken": "This user name is already taken."
       }
     },