diff --git a/src/serial.c b/src/serial.c
index 251f48c..2670c92 100644
--- a/src/serial.c
+++ b/src/serial.c
@@ -230,12 +230,9 @@ int
 send_number(u_int32_t number, int digits)
 {
 	char buf[CHAR_BUF_MAX];
-	ssize_t len;
 	int index = 0;
 
 	sprintf(buf, "%08X", number);
-	len = strlen(buf);
-
 	index = 8 - digits;
 
 	return send_message(&buf[index]);