diff --git a/demo/app/examples/groups.component.ts b/demo/app/examples/groups.component.ts
index 697f44410..6a9d11842 100644
--- a/demo/app/examples/groups.component.ts
+++ b/demo/app/examples/groups.component.ts
@@ -11,11 +11,14 @@ import { Component, ChangeDetectionStrategy } from '@angular/core';
         <label>Default group by key</label>
         ---html,true
         <ng-select [items]="accounts"
-                bindLabel="name"
-                bindValue="name"
-                groupBy="country"
-                [multiple]="true"
-                [(ngModel)]="selectedAccount">
+            bindLabel="name"
+            bindValue="name"
+            groupBy="country"
+            [multiple]="true"
+            [(ngModel)]="selectedAccount">
+            <ng-template ng-optgroup-tmp let-item="item">
+                {{item.country || 'Unnamed group'}}
+            </ng-template>
         </ng-select>
         ---
         <p>
@@ -25,11 +28,11 @@ import { Component, ChangeDetectionStrategy } from '@angular/core';
         <label>Group by function expression</label>
         ---html,true
         <ng-select [items]="accounts2"
-                bindLabel="name"
-                bindValue="name"
-                [groupBy]="groupByFn"
-                [multiple]="true"
-                [(ngModel)]="selectedAccount2">
+            bindLabel="name"
+            bindValue="name"
+            [groupBy]="groupByFn"
+            [multiple]="true"
+            [(ngModel)]="selectedAccount2">
         </ng-select>
         ---
         <p>
@@ -40,10 +43,13 @@ import { Component, ChangeDetectionStrategy } from '@angular/core';
         <label>With selectable groups</label>
         ---html,true
         <ng-select [items]="accounts3"
-                bindLabel="name"
-                groupBy="country"
-                [selectableGroup]="true"
-                [(ngModel)]="selectedAccount3">
+            bindLabel="name"
+            groupBy="country"
+            [selectableGroup]="true"
+            [(ngModel)]="selectedAccount3">
+            <ng-template ng-optgroup-tmp let-item="item">
+                {{item.country || 'Unnamed group'}}
+            </ng-template>
         </ng-select>
         ---
         <p>
@@ -58,6 +64,7 @@ export class SelectGroupsComponent {
         { name: 'Jill', email: 'jill@email.com', age: 15, child: { state: 'Active' } },
         { name: 'Henry', email: 'henry@email.com', age: 10, child: { state: 'Active' } },
         { name: 'Meg', email: 'meg@email.com', age: 7, country: null, child: { state: 'Active' } },
+        { name: 'Homer', email: 'homer@email.com', age: 47, country: '', child: { state: 'Active' } },
         { name: 'Samantha', email: 'samantha@email.com', age: 30, country: 'United States', child: { state: 'Active' } },
         { name: 'Amalie', email: 'amalie@email.com', age: 12, country: 'Argentina', child: { state: 'Active' } },
         { name: 'Estefanía', email: 'estefania@email.com', age: 21, country: 'Argentina', child: { state: 'Active' } },
diff --git a/src/ng-select/items-list.ts b/src/ng-select/items-list.ts
index 87561f7c2..3361a22e9 100644
--- a/src/ng-select/items-list.ts
+++ b/src/ng-select/items-list.ts
@@ -271,17 +271,17 @@ export class ItemsList {
 
     private _groupBy(items: NgOption[], prop: string | Function): OptionGroups {
         const isFn = isFunction(this._ngSelect.groupBy);
-        const groups = items.reduce((grouped, item) => {
+        const groups = new Map<string, NgOption[]>();
+        for (const item of items) {
             let key = isFn ? (<Function>prop).apply(this, [item.value]) : item.value[<string>prop];
-            key = key || undefined;
-            const group = grouped.get(key);
+            key = isDefined(key) ? key : undefined;
+            const group = groups.get(key);
             if (group) {
                 group.push(item);
             } else {
-                grouped.set(key, [item]);
+                groups.set(key, [item]);
             }
-            return grouped;
-        }, new Map<string, NgOption[]>());
+        }
         return groups;
     }
 
@@ -292,7 +292,7 @@ export class ItemsList {
         items.push(...withoutGroup);
         let i = withoutGroup.length;
         for (const key of Array.from(groups.keys())) {
-            if (!key) {
+            if (!isDefined(key)) {
                 continue;
             }
             const parent: NgOption = {
diff --git a/src/ng-select/ng-select.component.spec.ts b/src/ng-select/ng-select.component.spec.ts
index da15177a4..ba9e721e5 100644
--- a/src/ng-select/ng-select.component.spec.ts
+++ b/src/ng-select/ng-select.component.spec.ts
@@ -424,7 +424,7 @@ describe('NgSelectComponent', function () {
 
             fixture.componentInstance.selectedCity = { name: 'New city', id: 5 };
             tickAndDetectChanges(fixture);
-            fixture.componentInstance.cities = [...fixture.componentInstance.cities]
+            fixture.componentInstance.cities = [...fixture.componentInstance.cities];
             tickAndDetectChanges(fixture);
             expect(fixture.componentInstance.select.itemsList.markedItem.value).toEqual({ name: 'Vilnius', id: 1 });
         }));
@@ -552,7 +552,7 @@ describe('NgSelectComponent', function () {
             expect(fixture.componentInstance.selectedCityId).toEqual(1);
 
             // from model to component
-            fixture.componentInstance.selectedCityId = 2
+            fixture.componentInstance.selectedCityId = 2;
             tickAndDetectChanges(fixture);
 
             expect(fixture.componentInstance.select.selectedItems).toEqual([jasmine.objectContaining({
@@ -741,8 +741,7 @@ describe('NgSelectComponent', function () {
                         </ng-select>`);
 
                     const cmp = fixture.componentInstance;
-                    const cityId = cmp.cities[1].id.toString();
-                    cmp.selectedCityId = cityId;
+                    cmp.selectedCityId = cmp.cities[1].id.toString();
                    
                     cmp.compareWith = (city, model: string) => city.id === +model;
 
@@ -1022,7 +1021,7 @@ describe('NgSelectComponent', function () {
 
             it('should stop marked loop if all items disabled', fakeAsync(() => {
                 fixture.componentInstance.cities[0].disabled = true;
-                fixture.componentInstance.cities = [...fixture.componentInstance.cities]
+                fixture.componentInstance.cities = [...fixture.componentInstance.cities];
                 tickAndDetectChanges(fixture);
                 select.filter('vil');
                 tickAndDetectChanges(fixture);
@@ -1119,7 +1118,7 @@ describe('NgSelectComponent', function () {
                 const result = jasmine.objectContaining({
                     value: fixture.componentInstance.cities[2]
                 });
-                expect(fixture.componentInstance.select.itemsList.markedItem).toEqual(result)
+                expect(fixture.componentInstance.select.itemsList.markedItem).toEqual(result);
                 triggerKeyDownEvent(getNgSelectElement(fixture), KeyCode.Tab);
                 expect(fixture.componentInstance.select.selectedItems).toEqual([result]);
             }));
@@ -1201,7 +1200,7 @@ describe('NgSelectComponent', function () {
                 tick(200);
 
                 expect(fixture.componentInstance.selectedCity).toBeUndefined();
-                expect(select.itemsList.markedItem.label).toBe('Vilnius')
+                expect(select.itemsList.markedItem.label).toBe('Vilnius');
                 expect(findByLabel).toHaveBeenCalledWith('vil')
             }));
         });
@@ -1215,7 +1214,7 @@ describe('NgSelectComponent', function () {
             it('should select option and close dropdown', () => {
                 triggerKeyDownEvent(getNgSelectElement(fixture), KeyCode.Space);
                 triggerKeyDownEvent(getNgSelectElement(fixture), KeyCode.Enter);
-                expect(select.selectedItems[0].value).toEqual(fixture.componentInstance.cities[0])
+                expect(select.selectedItems[0].value).toEqual(fixture.componentInstance.cities[0]);
                 expect(select.isOpen).toBe(false);
             });
         });
@@ -1347,7 +1346,7 @@ describe('NgSelectComponent', function () {
             fixture.detectChanges();
             expect(fixture.componentInstance.select.selectedItems.length).toBe(1);
 
-            fixture.componentInstance.select.clearItem(fixture.componentInstance.cities[0])
+            fixture.componentInstance.select.clearItem(fixture.componentInstance.cities[0]);
             expect(fixture.componentInstance.select.selectedItems.length).toBe(0);
             tick();
         }));
@@ -1367,7 +1366,7 @@ describe('NgSelectComponent', function () {
             fixture.componentInstance.cities = [];
             fixture.detectChanges();
 
-            fixture.componentInstance.select.clearItem(selected)
+            fixture.componentInstance.select.clearItem(selected);
             expect(fixture.componentInstance.select.selectedItems.length).toBe(0);
             tick();
         }));
@@ -1671,9 +1670,9 @@ describe('NgSelectComponent', function () {
             it('should keep same ordering while unselecting', fakeAsync(() => {
                 fixture.componentInstance.selectedCities = [...fixture.componentInstance.cities.reverse()];
                 tickAndDetectChanges(fixture);
-                select.unselect(select.selectedItems[0])
-                select.unselect(select.selectedItems[0])
-                select.unselect(select.selectedItems[0])
+                select.unselect(select.selectedItems[0]);
+                select.unselect(select.selectedItems[0]);
+                select.unselect(select.selectedItems[0]);
                 expect(select.selectedItems.length).toBe(0);
                 expect(select.itemsList.filteredItems.length).toBe(3);
                 expect(select.itemsList.filteredItems[0].label).toBe('Vilnius');
@@ -1840,7 +1839,7 @@ describe('NgSelectComponent', function () {
             tickAndDetectChanges(fixture);
             tickAndDetectChanges(fixture);
             const selectEl: HTMLElement = select.elementRef.nativeElement;
-            const ngControl = selectEl.querySelector('.ng-select-container')
+            const ngControl = selectEl.querySelector('.ng-select-container');
             const placeholder: any = selectEl.querySelector('.ng-placeholder');
             expect(ngControl.classList.contains('ng-has-value')).toBeTruthy();
 
@@ -1855,7 +1854,7 @@ describe('NgSelectComponent', function () {
         it('should contain .ng-has-value when value was selected', fakeAsync(() => {
             tickAndDetectChanges(fixture);
             const selectEl: HTMLElement = fixture.componentInstance.select.elementRef.nativeElement;
-            const ngControl = selectEl.querySelector('.ng-select-container')
+            const ngControl = selectEl.querySelector('.ng-select-container');
             selectOption(fixture, KeyCode.ArrowDown, 2);
             tickAndDetectChanges(fixture);
             expect(ngControl.classList.contains('ng-has-value')).toBeTruthy();
@@ -1963,7 +1962,7 @@ describe('NgSelectComponent', function () {
             const result = jasmine.objectContaining({
                 value: fixture.componentInstance.cities[2]
             });
-            expect(fixture.componentInstance.select.itemsList.markedItem).toEqual(result)
+            expect(fixture.componentInstance.select.itemsList.markedItem).toEqual(result);
             triggerKeyDownEvent(getNgSelectElement(fixture), KeyCode.Enter);
             expect(fixture.componentInstance.select.selectedItems).toEqual([result]);
         }));
@@ -1984,7 +1983,7 @@ describe('NgSelectComponent', function () {
             const result = jasmine.objectContaining({
                 value: fixture.componentInstance.cities[2]
             });
-            expect(fixture.componentInstance.select.itemsList.markedItem).toEqual(result)
+            expect(fixture.componentInstance.select.itemsList.markedItem).toEqual(result);
             triggerKeyDownEvent(getNgSelectElement(fixture), KeyCode.Enter);
             expect(fixture.componentInstance.select.selectedItems).toEqual([result]);
         }));
@@ -2097,7 +2096,7 @@ describe('NgSelectComponent', function () {
         }));
 
         describe('with typeahead', () => {
-            let fixture: ComponentFixture<NgSelectTestCmp>
+            let fixture: ComponentFixture<NgSelectTestCmp>;
             beforeEach(() => {
                 fixture = createTestingModule(
                     NgSelectTestCmp,
@@ -2447,7 +2446,7 @@ describe('NgSelectComponent', function () {
                 tickAndDetectChanges(fixture);
                 tickAndDetectChanges(fixture);
                 triggerMousedown = () => {
-                    const control = fixture.debugElement.query(By.css('.ng-select-container'))
+                    const control = fixture.debugElement.query(By.css('.ng-select-container'));
                     control.triggerEventHandler('mousedown', createEvent({ target: { className: 'ng-control' } }));
                 };
             }));
@@ -2476,7 +2475,7 @@ describe('NgSelectComponent', function () {
                 tickAndDetectChanges(fixture);
                 tickAndDetectChanges(fixture);
                 triggerMousedown = () => {
-                    const control = fixture.debugElement.query(By.css('.ng-select-container'))
+                    const control = fixture.debugElement.query(By.css('.ng-select-container'));
                     control.triggerEventHandler('mousedown', createEvent({ target: { className: 'ng-clear' } }));
                 };
             }));
@@ -2528,7 +2527,7 @@ describe('NgSelectComponent', function () {
                 tickAndDetectChanges(fixture);
                 tickAndDetectChanges(fixture);
                 triggerMousedown = () => {
-                    const control = fixture.debugElement.query(By.css('.ng-select-container'))
+                    const control = fixture.debugElement.query(By.css('.ng-select-container'));
                     control.triggerEventHandler('mousedown', createEvent({ target: { className: 'ng-value-icon' } }));
                 };
             }));
@@ -2559,7 +2558,7 @@ describe('NgSelectComponent', function () {
                 fixture.componentInstance.selectedCity = fixture.componentInstance.cities[0];
                 tickAndDetectChanges(fixture);
                 triggerMousedown = () => {
-                    const control = fixture.debugElement.query(By.css('.ng-select-container'))
+                    const control = fixture.debugElement.query(By.css('.ng-select-container'));
                     control.triggerEventHandler('mousedown', createEvent({ target: { className: 'ng-arrow' } }));
                 };
             }));
@@ -2670,16 +2669,20 @@ describe('NgSelectComponent', function () {
             fixture.componentInstance.accounts.push(
                 <any>{ name: 'Henry', email: 'henry@email.com', age: 10 },
                 <any>{ name: 'Meg', email: 'meg@email.com', age: 7, country: null },
+                <any>{ name: 'Meg', email: 'meg@email.com', age: 7, country: '' },
             );
-            fixture.componentInstance.accounts = [...fixture.componentInstance.accounts]
+            fixture.componentInstance.accounts = [...fixture.componentInstance.accounts];
             tickAndDetectChanges(fixture);
 
-            const items = fixture.componentInstance.select.itemsList.items;
-            expect(items.length).toBe(16);
+            const items: NgOption[] = fixture.componentInstance.select.itemsList.items;
+            expect(items.length).toBe(18);
             expect(items[0].hasChildren).toBeUndefined();
             expect(items[0].parent).toBeUndefined();
             expect(items[1].hasChildren).toBeUndefined();
             expect(items[1].parent).toBeUndefined();
+            expect(items[16].hasChildren).toBeTruthy();
+            expect(items[16].label).toBe('');
+            expect(items[17].parent).toBeDefined();
         }));
 
         it('should group by group fn', fakeAsync(() => {