diff --git a/odex25_base/odex25_sign/models/res_users.py b/odex25_base/odex25_sign/models/res_users.py
index 9aafd233d..51fe60217 100644
--- a/odex25_base/odex25_sign/models/res_users.py
+++ b/odex25_base/odex25_sign/models/res_users.py
@@ -8,3 +8,12 @@ class ResUsers(models.Model):
 
     sign_signature = fields.Binary(string="Digital Signature", )
     sign_initials = fields.Binary(string="Digitial Initials",)
+
+
+    def __init__(self, pool, cr):
+        """Custom initialization of the model"""
+        super(ResUsers, self).__init__(pool, cr)
+
+        # Dynamically add fields to SELF_WRITEABLE_FIELDS and SELF_READABLE_FIELDS
+        type(self).SELF_WRITEABLE_FIELDS = list(self.SELF_WRITEABLE_FIELDS) + ['sign_signature', 'sign_initials']
+        type(self).SELF_READABLE_FIELDS = list(self.SELF_READABLE_FIELDS) + ['sign_signature', 'sign_initials']