diff --git a/drivers/staging/fwserial/fwserial.c b/drivers/staging/fwserial/fwserial.c
index cad9e98e0e6a..8859c75f16fa 100644
--- a/drivers/staging/fwserial/fwserial.c
+++ b/drivers/staging/fwserial/fwserial.c
@@ -578,7 +578,7 @@ static int fwtty_buffer_rx(struct fwtty_port *port, unsigned char *d, size_t n)
 	size_t size = (n + sizeof(struct buffered_rx) + 0xFF) & ~0xFF;
 
 	if (port->buffered + n > HIGH_WATERMARK) {
-		fwtty_err_ratelimited(port, "overflowed rx buffer: buffered: %d new: %ld wtrmk: %d",
+		fwtty_err_ratelimited(port, "overflowed rx buffer: buffered: %d new: %zu wtrmk: %d",
 				      port->buffered, n, HIGH_WATERMARK);
 		return 0;
 	}