diff --git a/lib/mutant/mutator/node/send.rb b/lib/mutant/mutator/node/send.rb
index 2f028280..2226bd93 100644
--- a/lib/mutant/mutator/node/send.rb
+++ b/lib/mutant/mutator/node/send.rb
@@ -61,7 +61,7 @@ module Mutant
 
         # Emit argument propagation
         #
-        # @return[undefined]
+        # @return [undefined]
         #
         # @api private
         #