diff --git a/doc/src/sgml/bgworker.sgml b/doc/src/sgml/bgworker.sgml
index 1151161a84..b0dde7564d 100644
--- a/doc/src/sgml/bgworker.sgml
+++ b/doc/src/sgml/bgworker.sgml
@@ -64,7 +64,10 @@ typedef struct BackgroundWorker
BGWORKER_SHMEM_ACCESS (requesting shared memory access)
and BGWORKER_BACKEND_DATABASE_CONNECTION (requesting the
ability to establish a database connection, through which it can later run
- transactions and queries).
+ transactions and queries). A background worker using
+ BGWORKER_BACKEND_DATABASE_CONNECTION to connect to
+ a database must also attach shared memory using
+ BGWORKER_SHMEM_ACCESS, or worker start-up will fail.