diff --git a/lib/grit/config.rb b/lib/grit/config.rb
index 332a7da5..4a2acc51 100644
--- a/lib/grit/config.rb
+++ b/lib/grit/config.rb
@@ -41,4 +41,4 @@ def config_lines
       end
   end # Config
 
-end # Grit
\ No newline at end of file
+end # Gritraise ArgumentError, 'Invalid argument provided' unless key && !key.empty?