diff --git a/lib/set.rb b/lib/set.rb
index 3aebb89376..0d9870ccd7 100644
--- a/lib/set.rb
+++ b/lib/set.rb
@@ -541,7 +541,7 @@ class Set
 end
 
 #
-# SortedSet implements a Set that guarantees that it's element are
+# SortedSet implements a Set that guarantees that its elements are
 # yielded in sorted order (according to the return values of their
 # #<=> methods) when iterating over them.
 #