diff --git a/lib/jekyll/theme_builder.rb b/lib/jekyll/theme_builder.rb
index 649df0ef..ca7dff69 100644
--- a/lib/jekyll/theme_builder.rb
+++ b/lib/jekyll/theme_builder.rb
@@ -82,6 +82,7 @@ class Jekyll::ThemeBuilder
   def initialize_git_repo
     Jekyll.logger.info "initialize", path.join(".git").to_s
     Dir.chdir(path.to_s) { `git init` }
+    write_file(".gitignore", template("gitignore"))
   end
 
   def user_name
diff --git a/lib/theme_template/gitignore.erb b/lib/theme_template/gitignore.erb
new file mode 100644
index 00000000..3eab3fcb
--- /dev/null
+++ b/lib/theme_template/gitignore.erb
@@ -0,0 +1,3 @@
+.sass-cache
+_site
+Gemfile.lock