diff --git a/source/reference/api/start.txt b/source/reference/api/start.txt
index 42a70b2c0..332c24aaa 100644
--- a/source/reference/api/start.txt
+++ b/source/reference/api/start.txt
@@ -99,8 +99,8 @@ Request Body Parameters
 
          .. include:: /includes/fact-verifier-buildIndexes
 
-         :red:`WARNING:` Do **not** manually build indexes while ``mongosync`` is 
-         performing a migration.  Wait until the migration is fully 
+         :red:`WARNING:` Do **not** manually build indexes on the destination cluster
+         while ``mongosync`` is performing a migration.  Wait until the migration is fully
          committed.
 
          For more information on the indexes it does build, see