diff --git a/core/dbt/task/clean.py b/core/dbt/task/clean.py
index 8fb828fe47f..c191037e7f6 100644
--- a/core/dbt/task/clean.py
+++ b/core/dbt/task/clean.py
@@ -26,8 +26,7 @@ def __is_protected_path(self, path):
         This function identifies protected paths, so as not to clean them.
         """
         abs_path = os.path.abspath(path)
-        protected_paths = self.config.model_paths + \
-            self.config.test_paths + ['.']
+        protected_paths = self.config.model_paths + self.config.test_paths + ["."]
         protected_abs_paths = [os.path.abspath(p) for p in protected_paths]
         return abs_path in set(protected_abs_paths) or self.__is_project_path(abs_path)