diff --git a/src/main.c b/src/main.c
index 6f2bd0a..94b80fc 100644
--- a/src/main.c
+++ b/src/main.c
@@ -138,6 +138,9 @@ void read_can(Tel *t, int soc) {
 void read_uart(Tel *t, int fd, SerialParser *uart_str) {
         char buf[128];
         int n = read(fd, buf, sizeof(buf));
+
+        if (n < 0) return; // -1 EAGAIN means empty
+
         if (n > 0) {
                 for (int i = 0; i < n; i++) {
                         char c = buf[i];