diff --git a/README.md b/README.md
index b39024ff545871a80f8716aa3b0a388ab669e461..80a444d4f6f763fed648e2f7b9a277c07318c03a 100644
--- a/README.md
+++ b/README.md
@@ -923,6 +923,9 @@ Now, any time Geocoder looks up "New York, NY" its results array will contain on
         }
       ]
     )
+    
+Note: 
+  Keys must be strings not symbols when calling `add_stub` or `set_default_stub`. For example `'latitude' =>` not `:latitude =>`.
 
 
 Command Line Interface