diff --git a/core/dbt/contracts/graph/unparsed.py b/core/dbt/contracts/graph/unparsed.py
index 83fe7c0cc5f..ea095db6501 100644
--- a/core/dbt/contracts/graph/unparsed.py
+++ b/core/dbt/contracts/graph/unparsed.py
@@ -277,7 +277,7 @@ def yaml_key(self) -> "str":
 
     def __post_serialize__(self, dct):
         dct = super().__post_serialize__(dct)
-        if 'freshness' not in dct and self.freshness is None:
+        if "freshness" not in dct and self.freshness is None:
             dct["freshness"] = None
         return dct