diff --git a/website/source/docs/builders/amazon.html.md b/website/source/docs/builders/amazon.html.md
index d54a28cef..3b1a177a9 100644
--- a/website/source/docs/builders/amazon.html.md
+++ b/website/source/docs/builders/amazon.html.md
@@ -184,7 +184,13 @@ Note that if you'd like to create a spot instance, you must also add:
 ec2:RequestSpotInstances,
 ec2:CancelSpotInstanceRequests,
 ec2:DescribeSpotInstanceRequests
-```  
+```
+
+If you have the `spot_price` parameter set to `auto`, you must also add:
+
+``` json
+ec2:DescribeSpotPriceHistory
+```
 
 ## Troubleshooting