diff --git a/source/reference/limits.txt b/source/reference/limits.txt
index 8670e86dce1..7c1807b1b4d 100644
--- a/source/reference/limits.txt
+++ b/source/reference/limits.txt
@@ -318,7 +318,7 @@ Operations
    MongoDB will only return sorted results on fields without an index
    *if* the combined size of all documents in the sort operation, plus
    a small overhead, is less than 32 megabytes.
-   
+
 .. _limit-agg-sort:
 
 .. limit:: Aggregation Pipeline Operation
@@ -404,6 +404,6 @@ Naming Restrictions
 
 .. limit:: Restrictions on Field Names
 
-   Field names cannot contain dots (i.e. ``.``), dollar signs
-   (i.e. ``$``), or null characters. See
+   Field names cannot contain dots (i.e. ``.``) or null characters, and they
+   must not start with a dollar sign (i.e. ``$``). See
    :ref:`faq-dollar-sign-escaping` for an alternate approach.