diff --git a/fs/cifs/smb2ops.c b/fs/cifs/smb2ops.c
index f83901c1c..b2a7238a3 100755
--- a/fs/cifs/smb2ops.c
+++ b/fs/cifs/smb2ops.c
@@ -82,6 +82,7 @@ smb2_add_credits(struct TCP_Server_Info *server,
 		*val = 65000; /* Don't get near 64K credits, avoid srv bugs */
 		pr_warn_once("server overflowed SMB3 credits\n");
 	}
+	WARN_ON_ONCE(server->in_flight == 0);
 	server->in_flight--;
 	if (server->in_flight == 0 && (optype & CIFS_OP_MASK) != CIFS_NEG_OP)
 		rc = change_conf(server);