diff --git a/lib/set.rb b/lib/set.rb
index 1fc14e7db2..c2792dedb1 100644
--- a/lib/set.rb
+++ b/lib/set.rb
@@ -100,7 +100,7 @@ class Set
     self
   end
 
-  # Converts the set to an array. (the order is uncertain)
+  # Converts the set to an array.  The order of elements is uncertain.
   def to_a
     @hash.keys
   end