diff --git a/munki/datastore/manifest.go b/munki/datastore/manifest.go
index 23c3a20..cc796f0 100644
--- a/munki/datastore/manifest.go
+++ b/munki/datastore/manifest.go
@@ -47,11 +47,11 @@ func (r *SimpleRepo) NewManifest(name string) (*munki.Manifest, error) {
 }
 
 // SaveManifest saves a manifest to the datastore
-func (r *SimpleRepo) SaveManifest(manifest *munki.Manifest) error {
-	if manifest.Filename == "" {
-		return errors.New("filename key must be set")
+func (r *SimpleRepo) SaveManifest(path string, manifest *munki.Manifest) error {
+	if path == "" {
+		return errors.New("must specify a manifest name")
 	}
-	manifestPath := fmt.Sprintf("%v/manifests/%v", r.Path, manifest.Filename)
+	manifestPath := fmt.Sprintf("%v/manifests/%v", r.Path, path)
 	file, err := os.OpenFile(manifestPath, os.O_WRONLY, 0755)
 	if err != nil {
 		return err
diff --git a/munki/munki/manifest.go b/munki/munki/manifest.go
index ab68644..92f70aa 100644
--- a/munki/munki/manifest.go
+++ b/munki/munki/manifest.go
@@ -5,7 +5,7 @@ type ManifestStore interface {
 	AllManifests() (*ManifestCollection, error)
 	Manifest(name string) (*Manifest, error)
 	NewManifest(name string) (*Manifest, error)
-	SaveManifest(manifest *Manifest) error
+	SaveManifest(path string, manifest *Manifest) error
 	DeleteManifest(name string) error
 }
 
diff --git a/munki/server/endpoint.go b/munki/server/endpoint.go
index a5d3485..63a5854 100644
--- a/munki/server/endpoint.go
+++ b/munki/server/endpoint.go
@@ -103,3 +103,23 @@ func makeReplaceManifestEndpoint(svc Service) endpoint.Endpoint {
 		return replaceManifestResponse{Manifest: manifest, Err: err}, nil
 	}
 }
+
+type updateManifestRequest struct {
+	Path string `plist:"filename" json:"filename"`
+	*munki.ManifestPayload
+}
+
+type updateManifestResponse struct {
+	*munki.Manifest
+	Err error `json:"error,omitempty" plist:"error,omitempty"`
+}
+
+func (r updateManifestResponse) error() error { return r.Err }
+
+func makeUpdateManifestEndpoint(svc Service) endpoint.Endpoint {
+	return func(ctx context.Context, request interface{}) (interface{}, error) {
+		req := request.(updateManifestRequest)
+		manifest, err := svc.UpdateManifest(ctx, req.Path, req.ManifestPayload)
+		return updateManifestResponse{Manifest: manifest, Err: err}, nil
+	}
+}
diff --git a/munki/server/service.go b/munki/server/service.go
index 13fc605..a575d71 100644
--- a/munki/server/service.go
+++ b/munki/server/service.go
@@ -13,6 +13,7 @@ type Service interface {
 	CreateManifest(ctx context.Context, name string, manifest *munki.Manifest) (*munki.Manifest, error)
 	ReplaceManifest(ctx context.Context, name string, manifest *munki.Manifest) (*munki.Manifest, error)
 	DeleteManifest(ctx context.Context, name string) error
+	UpdateManifest(ctx context.Context, name string, payload *munki.ManifestPayload) (*munki.Manifest, error)
 }
 
 type service struct {
@@ -32,8 +33,7 @@ func (svc service) CreateManifest(ctx context.Context, name string, manifest *mu
 	if err != nil {
 		return nil, err
 	}
-	manifest.Filename = name
-	if err := svc.repo.SaveManifest(manifest); err != nil {
+	if err := svc.repo.SaveManifest(name, manifest); err != nil {
 		return nil, err
 	}
 	return manifest, nil
@@ -50,8 +50,16 @@ func (svc service) ReplaceManifest(ctx context.Context, name string, manifest *m
 	return svc.CreateManifest(ctx, name, manifest)
 }
 
-func (svc service) UpdateManifest(ctx context.Context, name string, manifest *munki.Manifest) (*munki.Manifest, error) {
-	panic("not implemented")
+func (svc service) UpdateManifest(ctx context.Context, name string, payload *munki.ManifestPayload) (*munki.Manifest, error) {
+	manifest, err := svc.repo.Manifest(name)
+	if err != nil {
+		return nil, err
+	}
+	manifest.UpdateFromPayload(payload)
+	if err := svc.repo.SaveManifest(name, manifest); err != nil {
+		return nil, err
+	}
+	return manifest, nil
 }
 
 // NewService creates a new munki api service
diff --git a/munki/server/transport.go b/munki/server/transport.go
index 3ed35a6..a8cc908 100644
--- a/munki/server/transport.go
+++ b/munki/server/transport.go
@@ -65,6 +65,20 @@ func decodeReplaceManifestRequest(_ context.Context, r *http.Request) (interface
 	return request, nil
 }
 
+func decodeUpdateManifestRequest(_ context.Context, r *http.Request) (interface{}, error) {
+	var request updateManifestRequest
+	if err := json.NewDecoder(r.Body).Decode(&request.ManifestPayload); err != nil {
+		return nil, err
+	}
+	vars := mux.Vars(r)
+	path, ok := vars["path"]
+	if !ok {
+		return nil, errBadRouting
+	}
+	request.Path = path
+	return request, nil
+}
+
 // ServiceHandler creates an HTTP handler for the munki Service
 func ServiceHandler(ctx context.Context, svc Service, logger kitlog.Logger) http.Handler {
 	opts := []kithttp.ServerOption{
@@ -107,6 +121,13 @@ func ServiceHandler(ctx context.Context, svc Service, logger kitlog.Logger) http
 		encodeResponse,
 		opts...,
 	)
+	updateManifestHandler := kithttp.NewServer(
+		ctx,
+		makeUpdateManifestEndpoint(svc),
+		decodeUpdateManifestRequest,
+		encodeResponse,
+		opts...,
+	)
 	r := mux.NewRouter()
 	// manifests
 	r.Handle("/api/v1/manifests/{path}", showManifestHandler).Methods("GET")
@@ -114,6 +135,7 @@ func ServiceHandler(ctx context.Context, svc Service, logger kitlog.Logger) http
 	r.Handle("/api/v1/manifests", createManifestHandler).Methods("POST")
 	r.Handle("/api/v1/manifests/{path}", deleteManifestHandler).Methods("DELETE")
 	r.Handle("/api/v1/manifests/{path}", replaceManifestHandler).Methods("PUT")
+	r.Handle("/api/v1/manifests/{path}", updateManifestHandler).Methods("PATCH")
 	return r
 }
 
diff --git a/munki/server/transport_test.go b/munki/server/transport_test.go
index 5c37b13..57912a4 100644
--- a/munki/server/transport_test.go
+++ b/munki/server/transport_test.go
@@ -32,6 +32,27 @@ func TestShowManifests(t *testing.T) {
 	testShowManifestHTTP(t, server, "site_none", http.StatusNotFound)
 }
 
+func TestUpdateManifest(t *testing.T) {
+	server, _ := newServer(t)
+	defer server.Close()
+	manifests := []*munki.Manifest{
+		&munki.Manifest{
+			Filename: "update-manifest",
+			Catalogs: []string{"production", "testing"},
+		},
+	}
+
+	for _, m := range manifests {
+		os.Remove("testdata/testrepo/manifests/" + m.Filename)
+		testCreateManifestHTTP(t, server, m.Filename, m, http.StatusOK)
+		m1 := &munki.ManifestPayload{
+			Catalogs: &[]string{"foo"},
+		}
+		testUpdateManifestHTTP(t, server, m.Filename, m1, http.StatusOK)
+		os.Remove("testdata/testrepo/manifests/" + m.Filename)
+	}
+}
+
 func TestReplaceManifest(t *testing.T) {
 	server, _ := newServer(t)
 	defer server.Close()
@@ -134,6 +155,29 @@ func testReplaceManifestHTTP(t *testing.T, server *httptest.Server, path string,
 	}
 }
 
+func testUpdateManifestHTTP(t *testing.T, server *httptest.Server, path string, m *munki.ManifestPayload, expectedStatus int) {
+	client := http.DefaultClient
+	theURL := server.URL + "/api/v1/manifests/" + path
+	data, err := json.Marshal(m)
+	if err != nil {
+		t.Fatal(err)
+	}
+	body := ioutil.NopCloser(bytes.NewBuffer(data))
+	req, err := http.NewRequest("PATCH", theURL, body)
+	if err != nil {
+		t.Fatal(err)
+	}
+	resp, err := client.Do(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if resp.StatusCode != expectedStatus {
+		fmt.Println(theURL)
+		io.Copy(os.Stdout, resp.Body)
+		t.Fatal("expected", expectedStatus, "got", resp.StatusCode)
+	}
+}
+
 func testDeleteManifestHTTP(t *testing.T, server *httptest.Server, path string, expectedStatus int) {
 	client := http.DefaultClient
 	theURL := server.URL + "/api/v1/manifests/" + path