diff --git a/builtin/checkout.c b/builtin/checkout.c
index 22fb6c0cae..7cd01f62be 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -725,7 +725,10 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			 */
 			struct tree *result;
 			struct tree *work;
+			struct tree *old_tree;
 			struct merge_options o;
+			struct strbuf sb = STRBUF_INIT;
+
 			if (!opts->merge)
 				return 1;
 
@@ -735,6 +738,12 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			 */
 			if (!old_branch_info->commit)
 				return 1;
+			old_tree = get_commit_tree(old_branch_info->commit);
+
+			if (repo_index_has_changes(the_repository, old_tree, &sb))
+				die(_("cannot continue with staged changes in "
+				      "the following files:\n%s"), sb.buf);
+			strbuf_release(&sb);
 
 			/* Do more real merge */
 
@@ -772,7 +781,7 @@ static int merge_working_tree(const struct checkout_opts *opts,
 			ret = merge_trees(&o,
 					  get_commit_tree(new_branch_info->commit),
 					  work,
-					  get_commit_tree(old_branch_info->commit),
+					  old_tree,
 					  &result);
 			if (ret < 0)
 				exit(128);
diff --git a/t/t7201-co.sh b/t/t7201-co.sh
index f165582019..5990299fc9 100755
--- a/t/t7201-co.sh
+++ b/t/t7201-co.sh
@@ -224,15 +224,7 @@ test_expect_success 'switch to another branch while carrying a deletion' '
 	test_i18ngrep overwritten errs &&
 
 	test_must_fail git read-tree --quiet -m -u HEAD simple 2>errs &&
-	test_must_be_empty errs &&
-
-	git checkout --merge simple 2>errs &&
-	test_i18ngrep ! overwritten errs &&
-	git ls-files -u &&
-	test_must_fail git cat-file -t :0:two &&
-	test "$(git cat-file -t :1:two)" = blob &&
-	test "$(git cat-file -t :2:two)" = blob &&
-	test_must_fail git cat-file -t :3:two
+	test_must_be_empty errs
 '
 
 test_expect_success 'checkout to detach HEAD (with advice declined)' '