diff --git a/public_html/config.js b/public_html/config.js
index 3764210..339fb73 100644
--- a/public_html/config.js
+++ b/public_html/config.js
@@ -119,9 +119,17 @@ ChartBundleLayers = true;
 // Provide a Bing Maps API key here to enable the Bing imagery layer.
 // You can obtain a free key (with usage limits) at
 // https://www.bingmapsportal.com/ (you need a "basic key")
+//
+// Be sure to quote your key:
+//   BingMapsAPIKey = "your key here";
+//
 BingMapsAPIKey = null;
 
 // Provide a Mapzen API key here to enable the Mapzen vector tile layer.
 // You can obtain a free key at https://mapzen.com/developers/
 // (you need a "vector tiles" key)
+//
+// Be sure to quote your key:
+//   MapzenAPIKey = "your key here";
+//
 MapzenAPIKey = null;