diff --git a/lib/mutant/mutator/node/send.rb b/lib/mutant/mutator/node/send.rb
index 978fb205..e5232cba 100644
--- a/lib/mutant/mutator/node/send.rb
+++ b/lib/mutant/mutator/node/send.rb
@@ -25,7 +25,7 @@ module Mutant
           eql?:          %i[equal?],
           to_s:          %i[to_str],
           to_i:          %i[to_int],
-          to_a:          %i[to_ary],
+          to_a:          %i[to_ary to_set],
           to_h:          %i[to_hash],
           at:            %i[fetch key?],
           fetch:         %i[key?],
diff --git a/meta/send.rb b/meta/send.rb
index 730d1531..9617b598 100644
--- a/meta/send.rb
+++ b/meta/send.rb
@@ -144,6 +144,7 @@ Mutant::Meta::Example.add do
   mutation 'foo'
   mutation 'self.to_a'
   mutation 'foo.to_ary'
+  mutation 'foo.to_set'
 end
 
 Mutant::Meta::Example.add do