diff --git a/crispy_forms/tests/forms.py b/crispy_forms/tests/forms.py
index da8bf7734..71e681a8d 100644
--- a/crispy_forms/tests/forms.py
+++ b/crispy_forms/tests/forms.py
@@ -115,6 +115,7 @@ class CrispyEmptyChoiceTestModel(models.Model):
         choices=[("apple", "Apple"), ("pear", "Pear")],
         null=True,
         blank=True,
+        max_length=20,
     )