diff --git a/lib/github_changelog_generator/argv_parser.rb b/lib/github_changelog_generator/argv_parser.rb
index 168210d0..e62bae72 100755
--- a/lib/github_changelog_generator/argv_parser.rb
+++ b/lib/github_changelog_generator/argv_parser.rb
@@ -73,6 +73,7 @@ def parser
           options[:add_sections] = v
         end
         opts.on("--front-matter JSON", "Add YAML front matter. Formatted as JSON because it's easier to add on the command line.") do |v|
+          require "yaml"
           options[:frontmatter] = "#{JSON.parse(v).to_yaml}---\n"
         end
         opts.on("--pr-label LABEL", "Set up custom label for pull requests section. Default is \"**Merged pull requests:**\".") do |v|