diff --git a/lib/jekyll/commands/new_theme.rb b/lib/jekyll/commands/new_theme.rb
index e8919ae3..08eb4291 100644
--- a/lib/jekyll/commands/new_theme.rb
+++ b/lib/jekyll/commands/new_theme.rb
@@ -14,7 +14,9 @@ class Jekyll::Commands::NewTheme < Jekyll::Command
     end
 
     def process(args)
-      raise Jekyll::Errors::InvalidThemeName, "You must specify a theme name." if args.empty?
+      if !args || args.empty?
+        raise Jekyll::Errors::InvalidThemeName, "You must specify a theme name."
+      end
 
       new_theme_name = args.join("_")
       theme = Jekyll::ThemeBuilder.new(new_theme_name)