int first = 0, last = nr_ofs_deltas;
 
        while (first < last) {
-               int next = (first + last) / 2;
+               int next = first + (last - first) / 2;
                struct ofs_delta_entry *delta = &ofs_deltas[next];
                int cmp;
 
        int first = 0, last = nr_ref_deltas;
 
        while (first < last) {
-               int next = (first + last) / 2;
+               int next = first + (last - first) / 2;
                struct ref_delta_entry *delta = &ref_deltas[next];
                int cmp;
 
                                from_stdin = 1;
                        } else if (!strcmp(arg, "--fix-thin")) {
                                fix_thin_pack = 1;
-                       } else if (!strcmp(arg, "--strict")) {
-                               strict = 1;
-                               do_fsck_object = 1;
-                       } else if (skip_prefix(arg, "--strict=", &arg)) {
+                       } else if (skip_to_optional_arg(arg, "--strict", &arg)) {
                                strict = 1;
                                do_fsck_object = 1;
                                fsck_set_msg_types(&fsck_options, arg);
                                verify = 1;
                                show_stat = 1;
                                stat_only = 1;
-                       } else if (!strcmp(arg, "--keep")) {
-                               keep_msg = "";
-                       } else if (starts_with(arg, "--keep=")) {
-                               keep_msg = arg + 7;
+                       } else if (skip_to_optional_arg(arg, "--keep", &keep_msg)) {
+                               ; /* nothing to do */
                        } else if (starts_with(arg, "--threads=")) {
                                char *end;
                                nr_threads = strtoul(arg+10, &end, 0);