diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 8e4a1da954188757ea7059a23c9aef6ef00b3ba0..21ac19ff19cb2c3257f524f4aef90f0de2e8d342 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -1631,10 +1631,13 @@ SMB2_tcon(const unsigned int xid, struct cifs_ses *ses, const char *tree,
 	/*
 	 * 3.11 tcon req must be signed if not encrypted. See MS-SMB2 3.2.4.1.1
 	 * unless it is guest or anonymous user. See MS-SMB2 3.2.5.3.1
+	 * (Samba servers don't always set the flag so also check if null user)
 	 */
 	if ((ses->server->dialect == SMB311_PROT_ID) &&
 	    !smb3_encryption_required(tcon) &&
-	    !(ses->session_flags & (SMB2_SESSION_FLAG_IS_GUEST|SMB2_SESSION_FLAG_IS_NULL)))
+	    !(ses->session_flags &
+		    (SMB2_SESSION_FLAG_IS_GUEST|SMB2_SESSION_FLAG_IS_NULL)) &&
+	    ((ses->user_name != NULL) || (ses->sectype == Kerberos)))
 		req->sync_hdr.Flags |= SMB2_FLAGS_SIGNED;
 
 	memset(&rqst, 0, sizeof(struct smb_rqst));