diff --git a/src/tsconfig.strictNullChecks.json b/src/tsconfig.strictNullChecks.json
index 2ea4713a963..168f54c9358 100644
--- a/src/tsconfig.strictNullChecks.json
+++ b/src/tsconfig.strictNullChecks.json
@@ -549,6 +549,8 @@
 		"./vs/workbench/browser/actions/toggleStatusbarVisibility.ts",
 		"./vs/workbench/browser/actions/toggleTabsVisibility.ts",
 		"./vs/workbench/browser/actions/toggleZenMode.ts",
+		"./vs/workbench/browser/composite.ts",
+		"./vs/workbench/browser/panel.ts",
 		"./vs/workbench/browser/part.ts",
 		"./vs/workbench/browser/parts/editor/editorWidgets.ts",
 		"./vs/workbench/browser/parts/notifications/notificationsAlerts.ts",
@@ -734,8 +736,7 @@
 		"./vs/workbench/services/themes/common/workbenchThemeService.ts",
 		"./vs/workbench/services/title/common/titleService.ts",
 		"./vs/workbench/services/workspace/common/workspaceEditing.ts",
-		"./vs/workbench/test/electron-browser/api/mock.ts",
-		"./vs/workbench/browser/composite.ts"
+		"./vs/workbench/test/electron-browser/api/mock.ts"
 	],
 	"exclude": [
 		"./typings/require-monaco.d.ts"
diff --git a/src/vs/workbench/browser/panel.ts b/src/vs/workbench/browser/panel.ts
index aa6b2dad501..f827e998708 100644
--- a/src/vs/workbench/browser/panel.ts
+++ b/src/vs/workbench/browser/panel.ts
@@ -94,7 +94,7 @@ export abstract class TogglePanelAction extends Action {
 	private isPanelFocused(): boolean {
 		const activeElement = document.activeElement;
 
-		return this.isPanelActive() && activeElement && isAncestor(activeElement, this.partService.getContainer(Parts.PANEL_PART));
+		return !!(this.isPanelActive() && activeElement && isAncestor(activeElement, this.partService.getContainer(Parts.PANEL_PART)));
 	}
 }