diff --git a/leetcode-ruby.gemspec b/leetcode-ruby.gemspec
index 4135acb1..151f91fa 100644
--- a/leetcode-ruby.gemspec
+++ b/leetcode-ruby.gemspec
@@ -5,7 +5,7 @@ require 'English'
 ::Gem::Specification.new do |s|
   s.required_ruby_version = '>= 3.0'
   s.name = 'leetcode-ruby'
-  s.version = '7.5.7'
+  s.version = '7.5.7.1'
   s.license = 'MIT'
   s.files = ::Dir['lib/**/*.rb'] + %w[README.md]
   s.executable = 'leetcode-ruby'
diff --git a/lib/medium/784_letter_case_permutation.rb b/lib/medium/784_letter_case_permutation.rb
index a561fce9..ffc1e07a 100644
--- a/lib/medium/784_letter_case_permutation.rb
+++ b/lib/medium/784_letter_case_permutation.rb
@@ -16,6 +16,7 @@ def letter_case_permutation(s)
 # @param {Character[]} arr
 # @param {Integer} index
 # @param {String[]} result
+# @param {Void}
 def find_permutations(arr, index, result)
   if index == arr.size
     result << arr.join