diff --git a/lib/spack/spack/environment/environment.py b/lib/spack/spack/environment/environment.py
index 62967d13f66..a9dbf71c970 100644
--- a/lib/spack/spack/environment/environment.py
+++ b/lib/spack/spack/environment/environment.py
@@ -688,7 +688,12 @@ def regenerate(self, concretized_root_specs, force=False):
             return
 
         print(new_root)
-        print([(s, os.stat(os.path.join(os.path.dirname(new_root), s)).st_mtime) for s in os.listdir(os.path.dirname(new_root))])
+        print(
+            [
+                (s, os.stat(os.path.join(os.path.dirname(new_root), s)).st_mtime)
+                for s in os.listdir(os.path.dirname(new_root))
+            ]
+        )
         print(specs)
         if update_method == "exchange" and os.path.isdir(new_root):
             # If new_root is the newest thing in its directory, no need to update