diff --git a/lib/erb/formatter/command_line.rb b/lib/erb/formatter/command_line.rb
index 26c9ca2..51842d8 100644
--- a/lib/erb/formatter/command_line.rb
+++ b/lib/erb/formatter/command_line.rb
@@ -45,6 +45,11 @@ def initialize(argv, stdin: $stdin)
         puts parser
         exit
       end
+
+      parser.on("-v", "--version", "Show ERB::Formatter version number and quit") do
+        puts "ERB::Formatter #{ERB::Formatter::VERSION}"
+        exit
+      end
     end.parse!(@argv)
   end