diff --git a/main.go b/main.go
index b2ef240..2db8bcf 100644
--- a/main.go
+++ b/main.go
@@ -293,7 +293,7 @@ func licenseHeader(path string, tmpl *template.Template, data licenseData) ([]by
 		lic, err = executeTemplate(tmpl, data, "/**", " * ", " */")
 	case ".cc", ".cpp", ".cs", ".go", ".hcl", ".hh", ".hpp", ".m", ".mm", ".proto", ".rs", ".swift", ".dart", ".groovy", ".v", ".sv":
 		lic, err = executeTemplate(tmpl, data, "", "// ", "")
-	case ".py", ".sh", ".yaml", ".yml", ".dockerfile", "dockerfile", ".rb", "gemfile", ".tcl", ".bzl", ".pl", ".pp":
+	case ".py", ".sh", ".yaml", ".yml", ".dockerfile", "dockerfile", ".rb", "gemfile", ".ru", ".tcl", ".bzl", ".pl", ".pp":
 		lic, err = executeTemplate(tmpl, data, "", "# ", "")
 	case ".el", ".lisp":
 		lic, err = executeTemplate(tmpl, data, "", ";; ", "")
@@ -331,6 +331,7 @@ var head = []string{
 	"<!doctype",                // HTML doctype
 	"# encoding:",              // Ruby encoding
 	"# frozen_string_literal:", // Ruby interpreter instruction
+	"#\\",                      // Ruby Rack directive https://github.com/rack/rack/wiki/(tutorial)-rackup-howto
 	"<?php",                    // PHP opening tag
 	"# escape",                 // Dockerfile directive https://docs.docker.com/engine/reference/builder/#parser-directives
 	"# syntax",                 // Dockerfile directive https://docs.docker.com/engine/reference/builder/#parser-directives
diff --git a/main_test.go b/main_test.go
index 9b0df64..b1fff7d 100644
--- a/main_test.go
+++ b/main_test.go
@@ -241,6 +241,7 @@ func TestAddLicense(t *testing.T) {
 		{"<!DOCTYPE HTML>\ncontent", "<!DOCTYPE HTML>\n// HYS\n\ncontent", true},
 		{"# encoding: UTF-8\ncontent", "# encoding: UTF-8\n// HYS\n\ncontent", true},
 		{"# frozen_string_literal: true\ncontent", "# frozen_string_literal: true\n// HYS\n\ncontent", true},
+		{"#\\ -w -p 8765\ncontent", "#\\ -w -p 8765\n// HYS\n\ncontent", true},
 		{"<?php\ncontent", "<?php\n// HYS\n\ncontent", true},
 		{"# escape: `\ncontent", "# escape: `\n// HYS\n\ncontent", true},
 		{"# syntax: docker/dockerfile:1.3\ncontent", "# syntax: docker/dockerfile:1.3\n// HYS\n\ncontent", true},
@@ -316,7 +317,7 @@ func TestLicenseHeader(t *testing.T) {
 			"// HYS\n\n",
 		},
 		{
-			[]string{"f.py", "f.sh", "f.yaml", "f.yml", "f.dockerfile", "dockerfile", "f.rb", "gemfile", "f.tcl", "f.bzl", "f.pl", "f.pp"},
+			[]string{"f.py", "f.sh", "f.yaml", "f.yml", "f.dockerfile", "dockerfile", "f.rb", "gemfile", ".ru", "f.tcl", "f.bzl", "f.pl", "f.pp"},
 			"# HYS\n\n",
 		},
 		{
