diff --git a/litex/soc/software/bios/Makefile b/litex/soc/software/bios/Makefile
index 6fd21dd27..25217e11e 100644
--- a/litex/soc/software/bios/Makefile
+++ b/litex/soc/software/bios/Makefile
@@ -1,6 +1,11 @@
 include ../include/generated/variables.mak
 include $(SOC_DIRECTORY)/software/common.mak
 
+# Permit TFTP_SERVER_PORT override from shell environment / command line
+ifdef TFTP_SERVER_PORT
+CFLAGS += -DTFTP_SERVER_PORT=$(TFTP_SERVER_PORT)
+endif
+
 OBJECTS=isr.o sdram.o main.o boot-helper-$(CPU).o boot.o
 
 all: bios.bin
diff --git a/litex/soc/software/bios/boot.c b/litex/soc/software/bios/boot.c
index 91da5b177..edf4216a5 100644
--- a/litex/soc/software/bios/boot.c
+++ b/litex/soc/software/bios/boot.c
@@ -213,11 +213,17 @@ int serialboot(void)
 #define REMOTEIP4 100
 #endif
 
-static int tftp_get_v(unsigned int ip, const char *filename, char *buffer)
+#define DEFAULT_TFTP_SERVER_PORT 69  /* IANA well known port: UDP/69 */
+#ifndef TFTP_SERVER_PORT
+#define TFTP_SERVER_PORT DEFAULT_TFTP_SERVER_PORT
+#endif
+
+static int tftp_get_v(unsigned int ip, unsigned short server_port,
+    const char *filename, char *buffer)
 {
 	int r;
 
-	r = tftp_get(ip, filename, buffer);
+	r = tftp_get(ip, server_port, filename, buffer);
 	if(r > 0)
 		printf("Successfully downloaded %d bytes from %s over TFTP\n", r, filename);
 	else
@@ -232,6 +238,7 @@ void netboot(void)
 	int size;
 	unsigned int cmdline_adr, initrdstart_adr, initrdend_adr;
 	unsigned int ip;
+        unsigned short tftp_port;
 
 	printf("Booting from network...\n");
 	printf("Local IP : %d.%d.%d.%d\n", LOCALIP1, LOCALIP2, LOCALIP3, LOCALIP4);
@@ -241,13 +248,27 @@ void netboot(void)
 
 	microudp_start(macadr, IPTOINT(LOCALIP1, LOCALIP2, LOCALIP3, LOCALIP4));
 
-	if(tftp_get_v(ip, "boot.bin", (void *)MAIN_RAM_BASE) <= 0) {
+	tftp_port = TFTP_SERVER_PORT;
+	printf("Fetching from: UDP/%d\n", tftp_port);
+
+	size = tftp_get_v(ip, tftp_port, "boot.bin", (void *)MAIN_RAM_BASE);
+
+	if ((size <= 0) && (tftp_port != DEFAULT_TFTP_SERVER_PORT)) {
+		/* Try default TFTP port if timed out on non-standard port */
+		tftp_port = DEFAULT_TFTP_SERVER_PORT;
+		printf("Fetching from: UDP/%d\n", tftp_port);
+
+		size = tftp_get_v(ip, tftp_port, "boot.bin",
+			(void *)MAIN_RAM_BASE);
+        }
+
+        if (size <= 0) {
 		printf("Network boot failed\n");
 		return;
 	}
 
 	cmdline_adr = MAIN_RAM_BASE+0x1000000;
-	size = tftp_get_v(ip, "cmdline.txt", (void *)cmdline_adr);
+	size = tftp_get_v(ip, tftp_port, "cmdline.txt", (void *)cmdline_adr);
 	if(size <= 0) {
 		printf("No command line parameters found\n");
 		cmdline_adr = 0;
@@ -255,7 +276,7 @@ void netboot(void)
 		*((char *)(cmdline_adr+size)) = 0x00;
 
 	initrdstart_adr = MAIN_RAM_BASE+0x1002000;
-	size = tftp_get_v(ip, "initrd.bin", (void *)initrdstart_adr);
+	size = tftp_get_v(ip, tftp_port, "initrd.bin", (void *)initrdstart_adr);
 	if(size <= 0) {
 		printf("No initial ramdisk found\n");
 		initrdstart_adr = 0;
diff --git a/litex/soc/software/include/net/tftp.h b/litex/soc/software/include/net/tftp.h
index 7babb2d77..788731ba0 100644
--- a/litex/soc/software/include/net/tftp.h
+++ b/litex/soc/software/include/net/tftp.h
@@ -3,8 +3,10 @@
 
 #include <stdint.h>
 
-int tftp_get(uint32_t ip, const char *filename, void *buffer);
-int tftp_put(uint32_t ip, const char *filename, const void *buffer, int size);
+int tftp_get(uint32_t ip, uint16_t server_port, const char *filename,
+    void *buffer);
+int tftp_put(uint32_t ip, uint16_t server_port, const char *filename,
+    const void *buffer, int size);
 
 #endif /* __TFTP_H */
 
diff --git a/litex/soc/software/libnet/tftp.c b/litex/soc/software/libnet/tftp.c
index 8a9ecf219..3cbcec3a4 100644
--- a/litex/soc/software/libnet/tftp.c
+++ b/litex/soc/software/libnet/tftp.c
@@ -4,7 +4,7 @@
 #include <net/microudp.h>
 #include <net/tftp.h>
 
-#define PORT_OUT	69
+/* Local TFTP client port (arbitrary) */
 #define PORT_IN		7642
 
 enum {
@@ -100,7 +100,8 @@ static void rx_callback(uint32_t src_ip, uint16_t src_port,
 	}
 }
 
-int tftp_get(uint32_t ip, const char *filename, void *buffer)
+int tftp_get(uint32_t ip, uint16_t server_port, const char *filename,
+    void *buffer)
 {
 	int len;
 	int tries;
@@ -120,7 +121,7 @@ int tftp_get(uint32_t ip, const char *filename, void *buffer)
 	while(1) {
 		packet_data = microudp_get_tx_buffer();
 		len = format_request(packet_data, TFTP_RRQ, filename);
-		microudp_send(PORT_IN, PORT_OUT, len);
+		microudp_send(PORT_IN, server_port, len);
 		for(i=0;i<2000000;i++) {
 			microudp_service();
 			if((total_length > 0) || transfer_finished) break;
@@ -152,7 +153,8 @@ int tftp_get(uint32_t ip, const char *filename, void *buffer)
 	return total_length;
 }
 
-int tftp_put(uint32_t ip, const char *filename, const void *buffer, int size)
+int tftp_put(uint32_t ip, uint16_t server_port, const char *filename,
+    const void *buffer, int size)
 {
 	int len, send;
 	int tries;
@@ -172,7 +174,7 @@ int tftp_put(uint32_t ip, const char *filename, const void *buffer, int size)
 	while(1) {
 		packet_data = microudp_get_tx_buffer();
 		len = format_request(packet_data, TFTP_WRQ, filename);
-		microudp_send(PORT_IN, PORT_OUT, len);
+		microudp_send(PORT_IN, server_port, len);
 		for(i=0;i<2000000;i++) {
 			last_ack = -1;
 			microudp_service();