diff --git a/litex/soc/software/libnet/microudp.c b/litex/soc/software/libnet/microudp.c
index 90b73a7e1..be23d7336 100644
--- a/litex/soc/software/libnet/microudp.c
+++ b/litex/soc/software/libnet/microudp.c
@@ -111,7 +111,7 @@ struct ethernet_frame {
 
 typedef union {
 	struct ethernet_frame frame;
-	unsigned char raw[1532];
+	unsigned char raw[ETHMAC_SLOT_SIZE];
 } ethernet_buffer;