diff --git a/src/vs/workbench/electron-browser/workbench.main.ts b/src/vs/workbench/electron-browser/workbench.main.ts
index 4f16085b88b..08f779452ba 100644
--- a/src/vs/workbench/electron-browser/workbench.main.ts
+++ b/src/vs/workbench/electron-browser/workbench.main.ts
@@ -61,6 +61,7 @@ import 'vs/workbench/parts/extensions/electron-browser/extensionsViewlet'; // ca
 
 import 'vs/workbench/parts/explorers/browser/treeExplorer.contribution';
 import 'vs/workbench/parts/explorers/browser/treeExplorerActions.contribution';
+import 'vs/workbench/parts/explorers/browser/treeExplorerViewlet'; // can be packaged separately
 
 import 'vs/workbench/parts/output/browser/output.contribution';
 import 'vs/workbench/parts/output/browser/outputPanel'; // can be packaged separately