diff --git a/include/git2/config.h b/include/git2/config.h
index 332e62036d0..63293dbdaec 100644
--- a/include/git2/config.h
+++ b/include/git2/config.h
@@ -48,9 +48,13 @@ typedef enum {
 	 */
 	GIT_CONFIG_LEVEL_LOCAL = 5,
 
+	/** Worktree specific configuration file; $GIT_DIR/config.worktree
+	 */
+	GIT_CONFIG_LEVEL_WORKTREE = 6,
+
 	/** Application specific configuration file; freely defined by applications
 	 */
-	GIT_CONFIG_LEVEL_APP = 6,
+	GIT_CONFIG_LEVEL_APP = 7,
 
 	/** Represents the highest level available config file (i.e. the most
 	 * specific config file available that actually is loaded)
diff --git a/include/git2/repository.h b/include/git2/repository.h
index 0ff0856510f..9ad6176f940 100644
--- a/include/git2/repository.h
+++ b/include/git2/repository.h
@@ -499,6 +499,7 @@ typedef enum {
 	GIT_REPOSITORY_ITEM_PACKED_REFS,
 	GIT_REPOSITORY_ITEM_REMOTES,
 	GIT_REPOSITORY_ITEM_CONFIG,
+	GIT_REPOSITORY_ITEM_WORKTREE_CONFIG,
 	GIT_REPOSITORY_ITEM_INFO,
 	GIT_REPOSITORY_ITEM_HOOKS,
 	GIT_REPOSITORY_ITEM_LOGS,
diff --git a/src/libgit2/config.c b/src/libgit2/config.c
index 04f3ec2fee2..986d4ae7071 100644
--- a/src/libgit2/config.c
+++ b/src/libgit2/config.c
@@ -592,37 +592,55 @@ static const char *uses[] = {
 static int get_backend_for_use(git_config_backend **out,
 	git_config *cfg, const char *name, backend_use use)
 {
-	size_t i;
+	size_t len;
+	int error = 0;
 	backend_internal *backend;
+	git_config *cfg_single;
 
 	*out = NULL;
 
-	if (git_vector_length(&cfg->backends) == 0) {
+	len = git_vector_length(&cfg->backends);
+	if (len <= 0) {
+		/* todo: tweak message? */
 		git_error_set(GIT_ERROR_CONFIG,
 			"cannot %s value for '%s' when no config backends exist",
 			uses[use], name);
 		return GIT_ENOTFOUND;
 	}
 
-	git_vector_foreach(&cfg->backends, i, backend) {
-		if (!backend->backend->readonly) {
-			*out = backend->backend;
-			return 0;
+	if (len == 1) {
+		backend = git_vector_get(&cfg->backends, 0);
+
+		if (backend == NULL) {
+			/* todo: tweak message? */
+			git_error_set(GIT_ERROR_CONFIG, "failed to retrieve config backend");
+			return GIT_ENOTFOUND;
+		}
+
+		if (backend->backend->readonly) {
+			/* todo: tweak message? */
+			git_error_set(GIT_ERROR_CONFIG, "cannot %s value for '%s' when config backend is readonly", uses[use], name);
+			return GIT_ENOTFOUND;
 		}
+
+		*out = backend->backend;
+		return 0;
 	}
 
-	git_error_set(GIT_ERROR_CONFIG,
-		"cannot %s value for '%s' when all config backends are readonly",
-		uses[use], name);
-	return GIT_ENOTFOUND;
+	if ((error = git_config_open_level(&cfg_single, cfg, GIT_CONFIG_LEVEL_LOCAL)) < 0) {
+		return error;
+	}
+
+	return get_backend_for_use(out, cfg_single, name, use);
 }
 
 int git_config_delete_entry(git_config *cfg, const char *name)
 {
 	git_config_backend *backend;
+	int error = 0;
 
-	if (get_backend_for_use(&backend, cfg, name, BACKEND_USE_DELETE) < 0)
-		return GIT_ENOTFOUND;
+	if ((error = get_backend_for_use(&backend, cfg, name, BACKEND_USE_DELETE)) < 0)
+		return error;
 
 	return backend->del(backend, name);
 }
@@ -654,8 +672,8 @@ int git_config_set_string(git_config *cfg, const char *name, const char *value)
 		return -1;
 	}
 
-	if (get_backend_for_use(&backend, cfg, name, BACKEND_USE_SET) < 0)
-		return GIT_ENOTFOUND;
+	if ((error = get_backend_for_use(&backend, cfg, name, BACKEND_USE_SET)) < 0)
+		return error;
 
 	error = backend->set(backend, name, value);
 
@@ -1095,9 +1113,10 @@ int git_config_multivar_iterator_new(git_config_iterator **out, const git_config
 int git_config_set_multivar(git_config *cfg, const char *name, const char *regexp, const char *value)
 {
 	git_config_backend *backend;
+	int error = 0;
 
-	if (get_backend_for_use(&backend, cfg, name, BACKEND_USE_DELETE) < 0)
-		return GIT_ENOTFOUND;
+	if ((error = get_backend_for_use(&backend, cfg, name, BACKEND_USE_SET)) < 0)
+		return error;
 
 	return backend->set_multivar(backend, name, regexp, value);
 }
@@ -1105,9 +1124,10 @@ int git_config_set_multivar(git_config *cfg, const char *name, const char *regex
 int git_config_delete_multivar(git_config *cfg, const char *name, const char *regexp)
 {
 	git_config_backend *backend;
+	int error = 0;
 
-	if (get_backend_for_use(&backend, cfg, name, BACKEND_USE_DELETE) < 0)
-		return GIT_ENOTFOUND;
+	if ((error = get_backend_for_use(&backend, cfg, name, BACKEND_USE_DELETE)) < 0)
+		return error;
 
 	return backend->del_multivar(backend, name, regexp);
 }
diff --git a/src/libgit2/repository.c b/src/libgit2/repository.c
index 4eb3449133b..be938b5b9d0 100644
--- a/src/libgit2/repository.c
+++ b/src/libgit2/repository.c
@@ -58,6 +58,7 @@ static const struct {
 	{ GIT_REPOSITORY_ITEM_COMMONDIR, GIT_REPOSITORY_ITEM_GITDIR, "packed-refs", false },
 	{ GIT_REPOSITORY_ITEM_COMMONDIR, GIT_REPOSITORY_ITEM_GITDIR, "remotes", true },
 	{ GIT_REPOSITORY_ITEM_COMMONDIR, GIT_REPOSITORY_ITEM_GITDIR, "config", false },
+	{ GIT_REPOSITORY_ITEM_COMMONDIR, GIT_REPOSITORY_ITEM_GITDIR, "config.worktree", false },
 	{ GIT_REPOSITORY_ITEM_COMMONDIR, GIT_REPOSITORY_ITEM_GITDIR, "info", true },
 	{ GIT_REPOSITORY_ITEM_COMMONDIR, GIT_REPOSITORY_ITEM_GITDIR, "hooks", true },
 	{ GIT_REPOSITORY_ITEM_COMMONDIR, GIT_REPOSITORY_ITEM_GITDIR, "logs", true },
@@ -1291,6 +1292,12 @@ static int load_config(
 		return error;
 
 	if (repo) {
+		if ((error = git_repository__item_path(&config_path, repo, GIT_REPOSITORY_ITEM_WORKTREE_CONFIG)) == 0)
+			error = git_config_add_file_ondisk(cfg, config_path.ptr, GIT_CONFIG_LEVEL_WORKTREE, repo, 0);
+
+		if (error && error != GIT_ENOTFOUND)
+			goto on_error;
+
 		if ((error = git_repository__item_path(&config_path, repo, GIT_REPOSITORY_ITEM_CONFIG)) == 0)
 			error = git_config_add_file_ondisk(cfg, config_path.ptr, GIT_CONFIG_LEVEL_LOCAL, repo, 0);
 
@@ -1845,7 +1852,8 @@ static int check_repositoryformatversion(int *version, git_config *config)
 
 static const char *builtin_extensions[] = {
 	"noop",
-	"objectformat"
+	"objectformat",
+	"worktreeconfig",
 };
 
 static git_vector user_extensions = { 0, git__strcmp_cb };
diff --git a/tests/libgit2/config/configlevel.c b/tests/libgit2/config/configlevel.c
index 8422d32c944..3534fbc2c84 100644
--- a/tests/libgit2/config/configlevel.c
+++ b/tests/libgit2/config/configlevel.c
@@ -71,3 +71,21 @@ void test_config_configlevel__fetching_a_level_from_an_empty_compound_config_ret
 
 	git_config_free(cfg);
 }
+
+void test_config_configlevel__can_override_local_with_worktree(void)
+{
+	git_config *cfg;
+	git_buf buf = GIT_BUF_INIT;
+
+	cl_git_pass(git_config_new(&cfg));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config19"),
+		GIT_CONFIG_LEVEL_WORKTREE, NULL, 1));
+	cl_git_pass(git_config_add_file_ondisk(cfg, cl_fixture("config/config18"),
+		GIT_CONFIG_LEVEL_LOCAL, NULL, 1));
+
+	cl_git_pass(git_config_get_string_buf(&buf, cfg, "core.stringglobal"));
+	cl_assert_equal_s("don't find me!", buf.ptr);
+
+	git_buf_dispose(&buf);
+	git_config_free(cfg);
+}
diff --git a/tests/libgit2/config/readonly.c b/tests/libgit2/config/readonly.c
index a8901e394c0..0140bcb414d 100644
--- a/tests/libgit2/config/readonly.c
+++ b/tests/libgit2/config/readonly.c
@@ -49,6 +49,7 @@ void test_config_readonly__writing_to_cfg_with_rw_precedence_succeeds(void)
 void test_config_readonly__writing_to_cfg_with_ro_precedence_succeeds(void)
 {
 	git_config_backend *backend;
+	git_config *cfg_global;
 
 	cl_git_pass(git_config_backend_from_file(&backend, "local"));
 	backend->readonly = 1;
@@ -57,7 +58,10 @@ void test_config_readonly__writing_to_cfg_with_ro_precedence_succeeds(void)
 	cl_git_pass(git_config_backend_from_file(&backend, "global"));
 	cl_git_pass(git_config_add_backend(cfg, backend, GIT_CONFIG_LEVEL_GLOBAL, NULL, 0));
 
-	cl_git_pass(git_config_set_string(cfg, "foo.bar", "baz"));
+	cl_git_fail_with(GIT_ENOTFOUND, git_config_set_string(cfg, "foo.bar", "baz"));
+
+	git_config_open_global(&cfg_global, cfg);
+	cl_git_pass(git_config_set_string(cfg_global, "foo.bar", "baz"));
 
 	cl_assert(!git_fs_path_exists("local"));
 	cl_assert(git_fs_path_exists("global"));
diff --git a/tests/libgit2/core/opts.c b/tests/libgit2/core/opts.c
index 1aa095adf4c..cbef29f991d 100644
--- a/tests/libgit2/core/opts.c
+++ b/tests/libgit2/core/opts.c
@@ -34,9 +34,10 @@ void test_core_opts__extensions_query(void)
 
 	cl_git_pass(git_libgit2_opts(GIT_OPT_GET_EXTENSIONS, &out));
 
-	cl_assert_equal_sz(out.count, 2);
+	cl_assert_equal_sz(out.count, 3);
 	cl_assert_equal_s("noop", out.strings[0]);
 	cl_assert_equal_s("objectformat", out.strings[1]);
+	cl_assert_equal_s("worktreeconfig", out.strings[2]);
 
 	git_strarray_dispose(&out);
 }
@@ -49,10 +50,11 @@ void test_core_opts__extensions_add(void)
 	cl_git_pass(git_libgit2_opts(GIT_OPT_SET_EXTENSIONS, in, ARRAY_SIZE(in)));
 	cl_git_pass(git_libgit2_opts(GIT_OPT_GET_EXTENSIONS, &out));
 
-	cl_assert_equal_sz(out.count, 3);
+	cl_assert_equal_sz(out.count, 4);
 	cl_assert_equal_s("foo", out.strings[0]);
 	cl_assert_equal_s("noop", out.strings[1]);
 	cl_assert_equal_s("objectformat", out.strings[2]);
+	cl_assert_equal_s("worktreeconfig", out.strings[3]);
 
 	git_strarray_dispose(&out);
 }
@@ -65,10 +67,11 @@ void test_core_opts__extensions_remove(void)
 	cl_git_pass(git_libgit2_opts(GIT_OPT_SET_EXTENSIONS, in, ARRAY_SIZE(in)));
 	cl_git_pass(git_libgit2_opts(GIT_OPT_GET_EXTENSIONS, &out));
 
-	cl_assert_equal_sz(out.count, 3);
+	cl_assert_equal_sz(out.count, 4);
 	cl_assert_equal_s("bar", out.strings[0]);
 	cl_assert_equal_s("baz", out.strings[1]);
 	cl_assert_equal_s("objectformat", out.strings[2]);
+	cl_assert_equal_s("worktreeconfig", out.strings[3]);
 
 	git_strarray_dispose(&out);
 }
@@ -81,11 +84,12 @@ void test_core_opts__extensions_uniq(void)
 	cl_git_pass(git_libgit2_opts(GIT_OPT_SET_EXTENSIONS, in, ARRAY_SIZE(in)));
 	cl_git_pass(git_libgit2_opts(GIT_OPT_GET_EXTENSIONS, &out));
 
-	cl_assert_equal_sz(out.count, 4);
+	cl_assert_equal_sz(out.count, 5);
 	cl_assert_equal_s("bar", out.strings[0]);
 	cl_assert_equal_s("foo", out.strings[1]);
 	cl_assert_equal_s("noop", out.strings[2]);
 	cl_assert_equal_s("objectformat", out.strings[3]);
+	cl_assert_equal_s("worktreeconfig", out.strings[4]);
 
 	git_strarray_dispose(&out);
 }
diff --git a/tests/libgit2/remote/httpproxy.c b/tests/libgit2/remote/httpproxy.c
index 60fc67dec31..2ea5bf099b2 100644
--- a/tests/libgit2/remote/httpproxy.c
+++ b/tests/libgit2/remote/httpproxy.c
@@ -115,11 +115,14 @@ static void assert_global_config_match(const char *config, const char *expected)
 	git_remote *remote;
 	char *proxy;
 	git_config* cfg;
+	git_config* cfg_global;
 
 	if (config) {
 		cl_git_pass(git_config_open_default(&cfg));
-		git_config_set_string(cfg, config, expected);
+		cl_git_pass(git_config_open_global(&cfg_global, cfg));
+		git_config_set_string(cfg_global, config, expected);
 		git_config_free(cfg);
+		git_config_free(cfg_global);
 	}
 
 	cl_git_pass(git_remote_create_detached(&remote, "https://github.com/libgit2/libgit2"));
diff --git a/tests/libgit2/worktree/config.c b/tests/libgit2/worktree/config.c
index 81dcfe1fa51..c23cd044fba 100644
--- a/tests/libgit2/worktree/config.c
+++ b/tests/libgit2/worktree/config.c
@@ -27,7 +27,7 @@ void test_worktree_config__open(void)
 	git_config_free(cfg);
 }
 
-void test_worktree_config__set(void)
+void test_worktree_config__set_level_local(void)
 {
 	git_config *cfg;
 	int32_t val;
@@ -45,3 +45,31 @@ void test_worktree_config__set(void)
 	cl_assert_equal_i(val, 5);
 	git_config_free(cfg);
 }
+
+void test_worktree_config__set_level_worktree(void)
+{
+	git_config *cfg;
+	git_config *wtcfg;
+	int32_t val;
+
+	cl_git_pass(git_repository_config(&cfg, fixture.repo));
+	cl_git_pass(git_config_open_level(&wtcfg, cfg, GIT_CONFIG_LEVEL_WORKTREE));
+	cl_git_pass(git_config_set_int32(wtcfg, "worktree.specific", 42));
+
+	cl_git_pass(git_config_get_int32(&val, cfg, "worktree.specific"));
+	cl_assert_equal_i(val, 42);
+
+	/* reopen to verify config has been set */
+	git_config_free(cfg);
+	cl_git_pass(git_repository_config(&cfg, fixture.repo));
+	cl_git_pass(git_config_get_int32(&val, cfg, "worktree.specific"));
+	cl_assert_equal_i(val, 42);
+
+	cl_assert(git_config_delete_entry(cfg, "worktree.specific") == GIT_ENOTFOUND);
+
+	cl_git_pass(git_config_delete_entry(wtcfg, "worktree.specific"));
+	cl_assert(git_config_get_int32(&val, cfg, "worktree.specific") == GIT_ENOTFOUND);
+
+	git_config_free(cfg);
+	git_config_free(wtcfg);
+}