diff --git a/src/vs/workbench/services/files/electron-browser/streams.ts b/src/vs/workbench/services/files/electron-browser/streams.ts
index eabf557773a2e717ff2b2fc667935cf53b4c6b78..9b44d0c78a4ba3f52dabf3b47b1be238faca1cc5 100644
--- a/src/vs/workbench/services/files/electron-browser/streams.ts
+++ b/src/vs/workbench/services/files/electron-browser/streams.ts
@@ -43,7 +43,7 @@ function createSimpleWritable(provider: IFileSystemProvider, resource: URI, opts
 function createWritable(provider: IFileSystemProvider, resource: URI, opts: FileWriteOptions): Writable {
 	return new class extends Writable {
 		_fd: number;
-		_pos: number;
+		_pos: number = 0;
 		constructor(opts?) {
 			super(opts);
 		}