diff --git a/src/vs/workbench/browser/layout.ts b/src/vs/workbench/browser/layout.ts
index 494566ecb4a42a4ea8fb915d385316eb93b3b1b8..c00c5e1559e6e29759449211a9e3f498ddffbc30 100644
--- a/src/vs/workbench/browser/layout.ts
+++ b/src/vs/workbench/browser/layout.ts
@@ -104,6 +104,7 @@ export class WorkbenchLayout implements IVerticalSashLayoutProvider, IHorizontal
 		this.quickopen = quickopen;
 		this.toUnbind = [];
 		this.computedStyles = null;
+		this.panelHeightBeforeMaximized = 0;
 
 		this.sashX = new Sash(this.workbenchContainer.getHTMLElement(), this, {
 			baseSize: 5