diff --git a/platformio/util.py b/platformio/util.py
index d350c222..11364072 100644
--- a/platformio/util.py
+++ b/platformio/util.py
@@ -797,10 +797,8 @@ def merge_dicts(d1, d2, path=None):
 def ensure_udev_rules():
 
     def _rules_to_set(rules_path):
-        return set([
-            l.strip() for l in get_file_contents(rules_path).split("\n")
-            if l.strip() and not l.startswith("#")
-        ])
+        return set(l.strip() for l in get_file_contents(rules_path).split("\n")
+                   if l.strip() and not l.startswith("#"))
 
     if "linux" not in get_systype():
         return None