diff --git a/client/uart.c b/client/uart.c
index 71cea1109..5aefcf762 100644
--- a/client/uart.c
+++ b/client/uart.c
@@ -119,7 +119,7 @@ void uart_close(const serial_port sp) {
   fl.l_start  = 0;
   fl.l_len    = 0;
   fl.l_pid    = getpid();
-  fcntl(spu->fd, F_SETLK, &fl);
+  int err = fcntl(spu->fd, F_SETLK, &fl);
   close(spu->fd);
   free(sp);
 }