diff -up tftp-hpa-5.2/tftp/tftp.c.gcc10 tftp-hpa-5.2/tftp/tftp.c
--- tftp-hpa-5.2/tftp/tftp.c.gcc10	2020-05-04 00:56:28.787896509 +0200
+++ tftp-hpa-5.2/tftp/tftp.c	2020-05-04 00:58:42.502901005 +0200
@@ -48,7 +48,7 @@ extern int maxtimeout;
 #define PKTSIZE    SEGSIZE+4
 char ackbuf[PKTSIZE];
 int timeout;
-sigjmp_buf toplevel;
+extern sigjmp_buf toplevel;
 sigjmp_buf timeoutbuf;
 
 static void nak(int, const char *);