diff --git a/radicale_users.sh b/radicale_users.sh
index 5791816..78fb29e 100755
--- a/radicale_users.sh
+++ b/radicale_users.sh
@@ -76,6 +76,26 @@ prompt_password() {
 htpasswd_update() {
   local user="$1" password="$2"
   htpasswd -B -C "$DEFAULT_COST" -b "$USERS_FILE" "$user" "$password" >/dev/null
+  normalize_bcrypt_prefix "$user"
+}
+
+normalize_bcrypt_prefix() {
+  local user="$1"
+  if ! command -v python3 >/dev/null 2>&1; then
+    echo "⚠️  python3 no disponible: no se pudo normalizar el hash bcrypt de '$user' (prefijo \$2y\$)." >&2
+    echo "   Radicale solo acepta hashes \$2b\$, por lo que este usuario podría fallar." >&2
+    return
+  fi
+  python3 - "$USERS_FILE" "$user" <<'PY'
+import pathlib, re, sys
+path = pathlib.Path(sys.argv[1])
+user = sys.argv[2]
+data = path.read_text()
+pattern = re.compile(rf'^({re.escape(user)}:\$)2y', re.M)
+updated, count = pattern.subn(r'\g<1>2b', data)
+if count:
+    path.write_text(updated)
+PY
 }
 
 list_users() {