diff --git a/utils/ap51-flash/Makefile b/utils/ap51-flash/Makefile
index a30fa5d52..af5134ee5 100644
--- a/utils/ap51-flash/Makefile
+++ b/utils/ap51-flash/Makefile
@@ -30,7 +30,7 @@ define Package/ap51-flash
   URL:=http://dev.cloudtrax.com/wiki/ap51-flash-station
 endef
 
-TARGET_EXTRA_CFLAGS:=-DFLASH_FROM_FILE -DNO_LIBPCAP -D_GNU_SOURCE -DIPPORT_TFTP=69
+TARGET_EXTRA_CFLAGS:=-DFLASH_FROM_FILE -DNO_LIBPCAP -D_GNU_SOURCE
 ifeq ($(CONFIG_BIG_ENDIAN),y)
 	TARGET_EXTRA_CFLAGS:=$(TARGET_EXTRA_CFLAGS) -DUIP_CONF_BYTE_ORDER=1234
 endif
diff --git a/utils/ap51-flash/patches/100-ipport_tftp_def.patch b/utils/ap51-flash/patches/100-ipport_tftp_def.patch
new file mode 100644
index 000000000..ec728c84f
--- /dev/null
+++ b/utils/ap51-flash/patches/100-ipport_tftp_def.patch
@@ -0,0 +1,15 @@
+Index: ap51-flash-2016-10-16/proto.c
+===================================================================
+--- ap51-flash-2016-10-16.orig/proto.c
++++ ap51-flash-2016-10-16/proto.c
+@@ -29,6 +29,10 @@
+ #include "router_redboot.h"
+ #include "router_tftp_client.h"
+ 
++#ifndef IPPORT_TFTP
++#define IPPORT_TFTP	69
++#endif
++
+ #define TFTP_SRC_PORT 13337
+ #define REDBOOT_TELNET_SPORT 13337
+ #define REDBOOT_TELNET_DPORT 9000