1 files changed, 1 insertions, 1 deletions

diff --git a/server/helpers/custom-validators/users.ts b/server/helpers/custom-validators/users.ts
index f423d6317..b5b5642d6 100644
--- a/server/helpers/custom-validators/users.ts
+++ b/server/helpers/custom-validators/users.ts
@@ -18,7 +18,7 @@ function isUserVideoQuotaValid (value: string) {
 function isUserUsernameValid (value: string) {
   const max = USERS_CONSTRAINTS_FIELDS.USERNAME.max
   const min = USERS_CONSTRAINTS_FIELDS.USERNAME.min
-  return exists(value) && validator.matches(value, new RegExp(`^[a-zA-Z0-9._]{${min},${max}}$`))
+  return exists(value) && validator.matches(value, new RegExp(`^[a-z0-9._]{${min},${max}}$`))
 }
 
 function isUserDisplayNSFWValid (value: any) {