--- rigol-keygen-old.c  2013-09-25 11:05:05.144508478 +0200
+++ rigol-keygen.c  2013-09-25 11:04:54.217373970 +0200
@@ -141,7 +141,7 @@
 char * strtoupper(char *str) {
     char *newstr, *p;
     p = newstr = (char*) strdup((char*)str);
-    while ((*p++ = toupper(*p)));
+    while ((*p = toupper(*p))) p++;
     return newstr;
 }