diff --git a/contracts/models.py b/contracts/models.py
index 9e431ba24b0e84593654c422f2c69ca54cee042c..32bfbb8724523272cb35499b2c54d3b2f77a1165 100644
--- a/contracts/models.py
+++ b/contracts/models.py
@@ -20,7 +20,7 @@ from users.models import User
 class SubdomainValidatedURLField(models.URLField):
     validators = [
         URLValidator(schemes=("https",)),
-        RegexValidator(regex=r"https:\/\/.*\.pirati.cz(\/|$).*"),
+        RegexValidator(regex=r"https:\/\/(.*\.|)pirati.cz(\/|$).*"),
     ]