diff --git a/litex/soc/software/bios/boot.c b/litex/soc/software/bios/boot.c
index 635bd6493..e9257b1a9 100644
--- a/litex/soc/software/bios/boot.c
+++ b/litex/soc/software/bios/boot.c
@@ -178,14 +178,19 @@ void serialboot(void)
 
 #ifdef CSR_ETHMAC_BASE
 
+#ifndef LOCALIP1
 #define LOCALIP1 192
 #define LOCALIP2 168
 #define LOCALIP3 0
 #define LOCALIP4 42
+#endif
+
+#ifndef REMOTEIP1
 #define REMOTEIP1 192
 #define REMOTEIP2 168
 #define REMOTEIP3 0
 #define REMOTEIP4 14
+#endif
 
 static int tftp_get_v(unsigned int ip, const char *filename, char *buffer)
 {