diff --git a/api/handler.go b/api/handler.go
index 479bc27..fcd6d59 100644
--- a/api/handler.go
+++ b/api/handler.go
@@ -62,6 +62,7 @@ func Handler() *mux.Router {
 	m.Get(router.UnitType).Handler(handler(serveUnitType))
 	m.Get(router.CreateUnitType).Handler(handler(serveCreateUnitType))
 	m.Get(router.UnitTypes).Handler(handler(serveUnitTypeList))
+	m.Get(router.UpdateUnitType).Handler(handler(serveUpdateUnitType))
 
 	return m
 }
diff --git a/api/unit_types.go b/api/unit_types.go
index 34d6bb6..306be97 100644
--- a/api/unit_types.go
+++ b/api/unit_types.go
@@ -57,3 +57,22 @@ func serveUnitTypeList(w http.ResponseWriter, r *http.Request) error {
 
 	return writeJSON(w, unit_types)
 }
+
+func serveUpdateUnitType(w http.ResponseWriter, r *http.Request) error {
+	id, _ := strconv.ParseInt(mux.Vars(r)["Id"], 10, 0)
+	var unit_type models.UnitType
+	err := json.NewDecoder(r.Body).Decode(&unit_type)
+	if err != nil {
+		return err
+	}
+
+	updated, err := store.UnitTypes.Update(id, &unit_type)
+	if err != nil {
+		return err
+	}
+	if updated {
+		w.WriteHeader(http.StatusOK)
+	}
+
+	return writeJSON(w, unit_type)
+}
diff --git a/api/unit_types_test.go b/api/unit_types_test.go
index 385732f..09229e6 100644
--- a/api/unit_types_test.go
+++ b/api/unit_types_test.go
@@ -94,3 +94,33 @@ func TestUnitType_List(t *testing.T) {
 		t.Errorf("got unit_types %+v but wanted unit_types %+v", unit_types, want)
 	}
 }
+
+func TestUnitType_Update(t *testing.T) {
+	setup()
+
+	want := newUnitType()
+
+	calledPut := false
+	store.UnitTypes.(*models.MockUnitTypesService).Update_ = func(id int64, unit_type *models.UnitType) (bool, error) {
+		if id != want.Id {
+			t.Errorf("wanted request for unit_type %d but got %d", want.Id, id)
+		}
+		if !normalizeDeepEqual(want, unit_type) {
+			t.Errorf("wanted request for unit_type %d but got %d", want, unit_type)
+		}
+		calledPut = true
+		return true, nil
+	}
+
+	success, err := apiClient.UnitTypes.Update(want.Id, want)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !calledPut {
+		t.Error("!calledPut")
+	}
+	if !success {
+		t.Error("!success")
+	}
+}
diff --git a/datastore/unit_types.go b/datastore/unit_types.go
index 621ba60..a53c816 100644
--- a/datastore/unit_types.go
+++ b/datastore/unit_types.go
@@ -46,3 +46,26 @@ func (s *unitTypesStore) List(opt *models.UnitTypeListOptions) ([]*models.UnitTy
 	}
 	return unit_types, nil
 }
+
+func (s *unitTypesStore) Update(id int64, unit_type *models.UnitType) (bool, error) {
+	_, err := s.Get(id)
+	if err != nil {
+		return false, err
+	}
+
+	if id != unit_type.Id {
+		return false, models.ErrUnitTypeNotFound
+	}
+
+	unit_type.UpdatedAt = time.Now()
+	changed, err := s.dbh.Update(unit_type)
+	if err != nil {
+		return false, err
+	}
+
+	if changed == 0 {
+		return false, ErrNoRowsUpdated
+	}
+
+	return true, nil
+}
diff --git a/datastore/unit_types_test.go b/datastore/unit_types_test.go
index 7133a17..3675785 100644
--- a/datastore/unit_types_test.go
+++ b/datastore/unit_types_test.go
@@ -85,3 +85,23 @@ func TestUnitTypesStore_List_db(t *testing.T) {
 		t.Errorf("got unit_types %+v, want %+v", unit_types, want)
 	}
 }
+
+func TestUnitTypesStore_Update_db(t *testing.T) {
+	tx, _ := DB.Begin()
+	defer tx.Rollback()
+
+	unit_type := insertUnitType(t, tx)
+
+	d := NewDatastore(tx)
+
+	// Tweak it
+	unit_type.Name = "Updated Unit Type"
+	updated, err := d.UnitTypes.Update(unit_type.Id, unit_type)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !updated {
+		t.Error("!updated")
+	}
+}
diff --git a/models/unit_types.go b/models/unit_types.go
index 30ca352..8fb3478 100644
--- a/models/unit_types.go
+++ b/models/unit_types.go
@@ -36,6 +36,9 @@ type UnitTypesService interface {
 
 	// Create a unit type
 	Create(unit_type *UnitType) (bool, error)
+
+	// Update a unit type
+	Update(id int64, UnitType *UnitType) (bool, error)
 }
 
 var (
@@ -111,10 +114,32 @@ func (s *unitTypesService) List(opt *UnitTypeListOptions) ([]*UnitType, error) {
 	return unit_types, nil
 }
 
+func (s *unitTypesService) Update(id int64, unit_type *UnitType) (bool, error) {
+	strId := strconv.FormatInt(id, 10)
+
+	url, err := s.client.url(router.UpdateUnitType, map[string]string{"Id": strId}, nil)
+	if err != nil {
+		return false, err
+	}
+
+	req, err := s.client.NewRequest("PUT", url.String(), unit_type)
+	if err != nil {
+		return false, err
+	}
+
+	resp, err := s.client.Do(req, &unit_type)
+	if err != nil {
+		return false, err
+	}
+
+	return resp.StatusCode == http.StatusOK, nil
+}
+
 type MockUnitTypesService struct {
 	Get_    func(id int64) (*UnitType, error)
 	List_   func(opt *UnitTypeListOptions) ([]*UnitType, error)
 	Create_ func(unit_type *UnitType) (bool, error)
+	Update_ func(id int64, unit_type *UnitType) (bool, error)
 }
 
 var _ UnitTypesService = &MockUnitTypesService{}
@@ -139,3 +164,10 @@ func (s *MockUnitTypesService) List(opt *UnitTypeListOptions) ([]*UnitType, erro
 	}
 	return s.List_(opt)
 }
+
+func (s *MockUnitTypesService) Update(id int64, unit_type *UnitType) (bool, error) {
+	if s.Update_ == nil {
+		return false, nil
+	}
+	return s.Update_(id, unit_type)
+}
diff --git a/models/unit_types_test.go b/models/unit_types_test.go
index 1bcd154..1e76a43 100644
--- a/models/unit_types_test.go
+++ b/models/unit_types_test.go
@@ -112,3 +112,34 @@ func TestUnitTypeService_List(t *testing.T) {
 		t.Errorf("UnitTypes.List return %+v, want %+v", unit_types, want)
 	}
 }
+
+func TestUnitTypeService_Update(t *testing.T) {
+	setup()
+	defer teardown()
+
+	want := newUnitType()
+
+	var called bool
+	mux.HandleFunc(urlPath(t, router.UpdateUnitType, map[string]string{"Id": "1"}), func(w http.ResponseWriter, r *http.Request) {
+		called = true
+		testMethod(t, r, "PUT")
+		testBody(t, r, `{"id":1,"name":"Test Unit Type Updated","symbol":"x","createdAt":"0001-01-01T00:00:00Z","updatedAt":"0001-01-01T00:00:00Z","deletedAt":{"Time":"0001-01-01T00:00:00Z","Valid":false}}`+"\n")
+		w.WriteHeader(http.StatusOK)
+		writeJSON(w, want)
+	})
+
+	unit_type := newUnitType()
+	unit_type.Name = "Test Unit Type Updated"
+	updated, err := client.UnitTypes.Update(unit_type.Id, unit_type)
+	if err != nil {
+		t.Errorf("UnitTypes.Update returned error: %v", err)
+	}
+
+	if !updated {
+		t.Error("!updated")
+	}
+
+	if !called {
+		t.Fatal("!called")
+	}
+}
diff --git a/router/api.go b/router/api.go
index 78a4e41..9c9954f 100644
--- a/router/api.go
+++ b/router/api.go
@@ -56,6 +56,7 @@ func API() *mux.Router {
 	m.Path("/unit_types/").Methods("GET").Name(UnitTypes)
 	m.Path("/unit_types/").Methods("POST").Name(CreateUnitType)
 	m.Path("/unit_types/{Id:.+}").Methods("GET").Name(UnitType)
+	m.Path("/unit_types/{Id:.+}").Methods("PUT").Name(UpdateUnitType)
 
 	return m
 }
diff --git a/router/routes.go b/router/routes.go
index 031d42c..29e7317 100644
--- a/router/routes.go
+++ b/router/routes.go
@@ -44,4 +44,5 @@ const (
 	UnitType       = "unit_type:get"
 	CreateUnitType = "unit_type:create"
 	UnitTypes      = "unit_type:list"
+	UpdateUnitType = "unit_type:update"
 )