diff --git a/src/vs/workbench/browser/parts/activitybar/activitybarPart.ts b/src/vs/workbench/browser/parts/activitybar/activitybarPart.ts
index a6ecbcaeb4d616d6f071748f69df656c14763676..75bf886106e244d5c13516dc7810b21542842d52 100644
--- a/src/vs/workbench/browser/parts/activitybar/activitybarPart.ts
+++ b/src/vs/workbench/browser/parts/activitybar/activitybarPart.ts
@@ -286,7 +286,7 @@ export class ActivitybarPart extends Part implements IActivityBarService {
 
 	private createGlobalActivityActionBar(container: HTMLElement): void {
 		this.globalActivityActionBar = this._register(new ActionBar(container, {
-			actionViewItemProvider: action => this.instantiationService.createInstance(GlobalActivityActionViewItem, action, (theme: ITheme) => this.getActivitybarItemColors(theme)),
+			actionViewItemProvider: action => this.instantiationService.createInstance(GlobalActivityActionViewItem, action as ActivityAction, (theme: ITheme) => this.getActivitybarItemColors(theme)),
 			orientation: ActionsOrientation.VERTICAL,
 			ariaLabel: nls.localize('manage', "Manage"),
 			animated: false
diff --git a/src/vs/workbench/browser/parts/compositeBar.ts b/src/vs/workbench/browser/parts/compositeBar.ts
index a0681d0c7f1ae4f18e0d51fe02c53d3e49148365..2abdf594954ada391476271d5ce774175dde5d97 100644
--- a/src/vs/workbench/browser/parts/compositeBar.ts
+++ b/src/vs/workbench/browser/parts/compositeBar.ts
@@ -100,7 +100,7 @@ export class CompositeBar extends Widget implements ICompositeBar {
 					return this.compositeOverflowActionViewItem;
 				}
 				const item = this.model.findItem(action.id);
-				return item && this.instantiationService.createInstance(CompositeActionViewItem, action, item.pinnedAction, () => this.getContextMenuActions(), this.options.colors, this.options.icon, this);
+				return item && this.instantiationService.createInstance(CompositeActionViewItem, action as ActivityAction, item.pinnedAction, () => this.getContextMenuActions() as Action[], this.options.colors, this.options.icon, this);
 			},
 			orientation: this.options.orientation,
 			ariaLabel: nls.localize('activityBarAriaLabel', "Active View Switcher"),
diff --git a/src/vs/workbench/browser/parts/compositeBarActions.ts b/src/vs/workbench/browser/parts/compositeBarActions.ts
index 5ad81ef1e244eb62d859a557963b7d50059f5653..3d9dad112a09464ed34330c88025ee0674c8611e 100644
--- a/src/vs/workbench/browser/parts/compositeBarActions.ts
+++ b/src/vs/workbench/browser/parts/compositeBarActions.ts
@@ -362,8 +362,8 @@ export class CompositeOverflowActivityActionViewItem extends ActivityActionViewI
 
 	constructor(
 		action: ActivityAction,
-		private getOverflowingComposites: () => { id: string, name: string }[],
-		private getActiveCompositeId: () => string,
+		private getOverflowingComposites: () => { id: string, name?: string }[],
+		private getActiveCompositeId: () => string | undefined,
 		private getBadge: (compositeId: string) => IBadge,
 		private getCompositeOpenAction: (compositeId: string) => Action,
 		colors: (theme: ITheme) => ICompositeBarColors,
@@ -404,7 +404,7 @@ export class CompositeOverflowActivityActionViewItem extends ActivityActionViewI
 			if (suffix) {
 				action.label = nls.localize('numberBadge', "{0} ({1})", composite.name, suffix);
 			} else {
-				action.label = composite.name;
+				action.label = composite.name || '';
 			}
 
 			return action;