diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index e7325fe37f6148..1fbe156e67a4c7 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c
@@ -570,7 +570,10 @@ static int bisect_start(struct bisect_terms *terms, int no_checkout,
 	write_file(git_path_bisect_start(), "%s\n", start_head.buf);
 
 	if (no_checkout) {
-		get_oid(start_head.buf, &oid);
+		if (get_oid(start_head.buf, &oid) < 0) {
+			retval = error(_("invalid ref: '%s'"), start_head.buf);
+			goto finish;
+		}
 		if (update_ref(NULL, "BISECT_HEAD", &oid, NULL, 0,
 			       UPDATE_REFS_MSG_ON_ERR)) {
 			retval = -1;
diff --git a/builtin/rebase.c b/builtin/rebase.c
index ba3a574e4022c3..db6ca9bd7d4c4e 100644
--- a/builtin/rebase.c
+++ b/builtin/rebase.c
@@ -1203,7 +1203,7 @@ static int rebase_config(const char *var, const char *value, void *data)
 		if (git_config_bool(var, value))
 			opts->flags |= REBASE_DIFFSTAT;
 		else
-			opts->flags &= !REBASE_DIFFSTAT;
+			opts->flags &= ~REBASE_DIFFSTAT;
 		return 0;
 	}