diff --git a/docs/t-sql/functions/bit-count-transact-sql.md b/docs/t-sql/functions/bit-count-transact-sql.md
index 3c5e2ff3695..8c12a6e7635 100644
--- a/docs/t-sql/functions/bit-count-transact-sql.md
+++ b/docs/t-sql/functions/bit-count-transact-sql.md
@@ -49,6 +49,8 @@ Any integer or binary expression that isn't a large object ([LOB](#remarks)).
 
 For example, `SELECT BIT_COUNT (CAST (-1 AS SMALLINT))` and `SELECT BIT_COUNT (CAST (-1 AS INT))` return `16` and `32` respectively. This is intended, as the binary representation of `-1` can have a different number of bits set to `1` depending on the data type.
 
+If *expression_value* is `NULL`, `BIT_COUNT` returns `NULL`.
+
 ## Remarks
 
 Distributed Query functionality for the bit manipulation functions within linked server or ad hoc queries (`OPENQUERY`) aren't supported.