--- a/tftp/tftp.c	
+++ a/tftp/tftp.c	
@@ -52,7 +52,7 @@ sigjmp_buf toplevel;
 sigjmp_buf timeoutbuf;
 
 static void nak(int, const char *);
-static int makerequest(int, const char *, struct tftphdr *, const char *);
+static int makerequest(int, const char *, void *, const char *);
 static void printstats(const char *, unsigned long);
 static void startclock(void);
 static void stopclock(void);
@@ -276,17 +276,23 @@ void tftp_recvfile(int fd, const char *name, const char *mode)
 
 static int
 makerequest(int request, const char *name,
-            struct tftphdr *tp, const char *mode)
+            void *p, const char *mode)
 {
     char *cp;
+    struct tftphdr *tp = p;
+    size_t namelen, modelen;
 
     tp->th_opcode = htons((u_short) request);
-    cp = (char *)&(tp->th_stuff);
+    cp = (char*)p + offsetof(struct tftphdr, th_stuff);
+    namelen = strlen(name);
+    modelen = strlen(mode);
+    if (namelen + modelen + 2 > SEGSIZE)
+	    perror("Filename is too long");
     strcpy(cp, name);
-    cp += strlen(name);
+    cp += namelen;
     *cp++ = '\0';
     strcpy(cp, mode);
-    cp += strlen(mode);
+    cp += modelen;
     *cp++ = '\0';
     return (cp - (char *)tp);
 }