diff --git a/source/app/models/main.py b/source/app/models/main.py
index fc312f2..dfc0eee 100644
--- a/source/app/models/main.py
+++ b/source/app/models/main.py
@@ -2783,6 +2783,7 @@ class PreFacturas(BaseModel):
 
         data['comprobante'] = obj
         data['comprobante']['version'] = CURRENT_CFDI
+        data['comprobante']['folio'] = str(data['comprobante']['folio'])
         data['comprobante']['seriefolio'] = '{}-{}'.format(
             data['comprobante']['serie'], data['comprobante']['folio'])
         data['comprobante']['fecha'] = str(data['comprobante']['fecha'])