--- xinstall.c.old	2016-01-31 19:02:34.000000000 -0500
+++ xinstall.c	2016-01-31 19:04:22.266320000 -0500
@@ -316,7 +316,9 @@
 		uid = (uid_t)-1;
 
 	if (fflags != NULL && !dounpriv) {
-		if (strtofflags(&fflags, &fset, NULL))
+		if (*fflags >= '0' && *fflags <= '7') {
+			fset = strtol(fflags, NULL, 8);
+		} else if (strtofflags(&fflags, &fset, NULL))
 			errx(EX_USAGE, "%s: invalid flag", fflags);
 		iflags |= SETFLAGS;
 	}