diff --git a/sdk-api-src/content/restartmanager/nf-restartmanager-rmstartsession.md b/sdk-api-src/content/restartmanager/nf-restartmanager-rmstartsession.md
index a6ea0fadf585..e47be2906dfd 100644
--- a/sdk-api-src/content/restartmanager/nf-restartmanager-rmstartsession.md
+++ b/sdk-api-src/content/restartmanager/nf-restartmanager-rmstartsession.md
@@ -64,7 +64,7 @@ Reserved. This parameter should be 0.
 
 ### -param strSessionKey [out]
 
-A <b>null</b>-terminated string that contains the session key to the new session. The string must be allocated before calling  the <b>RmStartSession</b> function.
+A <b>null</b>-terminated string that contains the session key to the new session. The string of size `CCH_RM_SESSION_KEY + 1` must be allocated before calling the <b>RmStartSession</b> function.
 
 ## -returns
 
@@ -163,4 +163,4 @@ A secondary installer can join an existing Restart Manager session by calling th
 
 
 
-<a href="/windows/desktop/api/restartmanager/nf-restartmanager-rmjoinsession">RmJoinSession</a>
\ No newline at end of file
+<a href="/windows/desktop/api/restartmanager/nf-restartmanager-rmjoinsession">RmJoinSession</a>