diff --git a/src/vs/workbench/api/electron-browser/mainThreadFileSystem.ts b/src/vs/workbench/api/electron-browser/mainThreadFileSystem.ts
index 164d458a3ed..e93e8173175 100644
--- a/src/vs/workbench/api/electron-browser/mainThreadFileSystem.ts
+++ b/src/vs/workbench/api/electron-browser/mainThreadFileSystem.ts
@@ -99,15 +99,13 @@ class RemoteFileSystemProvider implements IFileSystemProvider {
 	}
 
 	readFile(resource: URI): TPromise<Uint8Array> {
-		return this._proxy.$readFile(this._handle, resource).then(encoded => {
-			return Buffer.from(encoded, 'base64');
-		});
+		return this._proxy.$readFile(this._handle, resource);
 	}
 
 	writeFile(resource: URI, content: Uint8Array, opts: FileWriteOptions): TPromise<void> {
 		let encoded = Buffer.isBuffer(content)
-			? content.toString('base64')
-			: Buffer.from(content.buffer, content.byteOffset, content.byteLength).toString('base64');
+			? content
+			: Buffer.from(content.buffer, content.byteOffset, content.byteLength);
 		return this._proxy.$writeFile(this._handle, resource, encoded, opts);
 	}
 
diff --git a/src/vs/workbench/api/node/extHost.protocol.ts b/src/vs/workbench/api/node/extHost.protocol.ts
index edb764542ad..477f60f32b7 100644
--- a/src/vs/workbench/api/node/extHost.protocol.ts
+++ b/src/vs/workbench/api/node/extHost.protocol.ts
@@ -679,8 +679,8 @@ export interface ExtHostWorkspaceShape {
 export interface ExtHostFileSystemShape {
 	$stat(handle: number, resource: UriComponents): TPromise<IStat>;
 	$readdir(handle: number, resource: UriComponents): TPromise<[string, FileType][]>;
-	$readFile(handle: number, resource: UriComponents): TPromise<string>;
-	$writeFile(handle: number, resource: UriComponents, base64Encoded: string, opts: FileWriteOptions): TPromise<void>;
+	$readFile(handle: number, resource: UriComponents): TPromise<Buffer>;
+	$writeFile(handle: number, resource: UriComponents, content: Buffer, opts: FileWriteOptions): TPromise<void>;
 	$rename(handle: number, resource: UriComponents, target: UriComponents, opts: FileOverwriteOptions): TPromise<void>;
 	$copy(handle: number, resource: UriComponents, target: UriComponents, opts: FileOverwriteOptions): TPromise<void>;
 	$mkdir(handle: number, resource: UriComponents): TPromise<void>;
diff --git a/src/vs/workbench/api/node/extHostFileSystem.ts b/src/vs/workbench/api/node/extHostFileSystem.ts
index 732d21cd761..5bacd68adf3 100644
--- a/src/vs/workbench/api/node/extHostFileSystem.ts
+++ b/src/vs/workbench/api/node/extHostFileSystem.ts
@@ -159,16 +159,16 @@ export class ExtHostFileSystem implements ExtHostFileSystemShape {
 		return asWinJsPromise(() => this._fsProvider.get(handle).readDirectory(URI.revive(resource)));
 	}
 
-	$readFile(handle: number, resource: UriComponents): TPromise<string> {
+	$readFile(handle: number, resource: UriComponents): TPromise<Buffer> {
 		return asWinJsPromise(() => {
 			return this._fsProvider.get(handle).readFile(URI.revive(resource));
 		}).then(data => {
-			return Buffer.isBuffer(data) ? data.toString('base64') : Buffer.from(data.buffer, data.byteOffset, data.byteLength).toString('base64');
+			return Buffer.isBuffer(data) ? data : Buffer.from(data.buffer, data.byteOffset, data.byteLength);
 		});
 	}
 
-	$writeFile(handle: number, resource: UriComponents, base64Content: string, opts: files.FileWriteOptions): TPromise<void> {
-		return asWinJsPromise(() => this._fsProvider.get(handle).writeFile(URI.revive(resource), Buffer.from(base64Content, 'base64'), opts));
+	$writeFile(handle: number, resource: UriComponents, content: Buffer, opts: files.FileWriteOptions): TPromise<void> {
+		return asWinJsPromise(() => this._fsProvider.get(handle).writeFile(URI.revive(resource), content, opts));
 	}
 
 	$delete(handle: number, resource: UriComponents, opts: files.FileDeleteOptions): TPromise<void> {