#define NOERR() {if (ISERR()) return;} /* if error seen, return */
#define NOERRN() {if (ISERR()) return NULL;} /* NOERR with retval */
#define NOERRZ() {if (ISERR()) return 0;} /* NOERR with retval */
-#define INSIST(c, e) (void)((c) ? 0 : ERR(e)) /* if condition false, error */
+#define INSIST(c, e) (void)((c) ? (void)0 : ERR(e)) /* if condition false, error */
#define NOTE(b) (v->re->re_info |= (b)) /* note visible condition */
#define EMPTYARC(x, y) newarc(v->nfa, EMPTY, 0, x, y)