diff --git a/src/vs/workbench/api/browser/mainThreadCommands.ts b/src/vs/workbench/api/browser/mainThreadCommands.ts
index 38f6ac66927..b441871a34d 100644
--- a/src/vs/workbench/api/browser/mainThreadCommands.ts
+++ b/src/vs/workbench/api/browser/mainThreadCommands.ts
@@ -9,6 +9,7 @@ import { ExtHostContext, MainThreadCommandsShape, ExtHostCommandsShape, MainCont
 import { extHostNamedCustomer } from 'vs/workbench/api/common/extHostCustomers';
 import { revive } from 'vs/base/common/marshalling';
 import { IExtensionService } from 'vs/workbench/services/extensions/common/extensions';
+import { SerializableObjectWithBuffers } from 'vs/workbench/services/extensions/common/proxyIdentifier';
 
 @extHostNamedCustomer(MainContext.MainThreadCommands)
 export class MainThreadCommands implements MainThreadCommandsShape {
@@ -72,7 +73,10 @@ export class MainThreadCommands implements MainThreadCommandsShape {
 		}
 	}
 
-	async $executeCommand<T>(id: string, args: any[], retry: boolean): Promise<T | undefined> {
+	async $executeCommand<T>(id: string, args: any[] | SerializableObjectWithBuffers<any[]>, retry: boolean): Promise<T | undefined> {
+		if (args instanceof SerializableObjectWithBuffers) {
+			args = args.value;
+		}
 		for (let i = 0; i < args.length; i++) {
 			args[i] = revive(args[i]);
 		}
diff --git a/src/vs/workbench/api/common/extHost.protocol.ts b/src/vs/workbench/api/common/extHost.protocol.ts
index d8fe3a603ed..ebc632f4b33 100644
--- a/src/vs/workbench/api/common/extHost.protocol.ts
+++ b/src/vs/workbench/api/common/extHost.protocol.ts
@@ -140,7 +140,7 @@ export interface MainThreadClipboardShape extends IDisposable {
 export interface MainThreadCommandsShape extends IDisposable {
 	$registerCommand(id: string): void;
 	$unregisterCommand(id: string): void;
-	$executeCommand<T>(id: string, args: any[], retry: boolean): Promise<T | undefined>;
+	$executeCommand<T>(id: string, args: any[] | SerializableObjectWithBuffers<any[]>, retry: boolean): Promise<T | undefined>;
 	$getCommands(): Promise<string[]>;
 }
 
diff --git a/src/vs/workbench/api/common/extHostCommands.ts b/src/vs/workbench/api/common/extHostCommands.ts
index e9610ab12b4..3816f690683 100644
--- a/src/vs/workbench/api/common/extHostCommands.ts
+++ b/src/vs/workbench/api/common/extHostCommands.ts
@@ -22,6 +22,8 @@ import { createDecorator } from 'vs/platform/instantiation/common/instantiation'
 import { IExtHostRpcService } from 'vs/workbench/api/common/extHostRpcService';
 import { ISelection } from 'vs/editor/common/core/selection';
 import { TestItemImpl } from 'vs/workbench/api/common/extHostTestingPrivateApi';
+import { VSBuffer } from 'vs/base/common/buffer';
+import { SerializableObjectWithBuffers } from 'vs/workbench/services/extensions/common/proxyIdentifier';
 
 interface CommandHandler {
 	callback: Function;
@@ -84,6 +86,9 @@ export class ExtHostCommands implements ExtHostCommandsShape {
 						if (Range.isIRange((obj as modes.Location).range) && URI.isUri((obj as modes.Location).uri)) {
 							return extHostTypeConverter.location.to(obj);
 						}
+						if (obj instanceof VSBuffer) {
+							return obj.buffer.buffer;
+						}
 						if (!Array.isArray(obj)) {
 							return obj;
 						}
@@ -164,6 +169,7 @@ export class ExtHostCommands implements ExtHostCommandsShape {
 
 		} else {
 			// automagically convert some argument types
+			let hasBuffers = false;
 			const toArgs = cloneAndChange(args, function (value) {
 				if (value instanceof extHostTypes.Position) {
 					return extHostTypeConverter.Position.from(value);
@@ -173,6 +179,12 @@ export class ExtHostCommands implements ExtHostCommandsShape {
 					return extHostTypeConverter.location.from(value);
 				} else if (extHostTypes.NotebookRange.isNotebookRange(value)) {
 					return extHostTypeConverter.NotebookRange.from(value);
+				} else if (value instanceof ArrayBuffer) {
+					hasBuffers = true;
+					return VSBuffer.wrap(new Uint8Array(value));
+				} else if (value instanceof Uint8Array) {
+					hasBuffers = true;
+					return VSBuffer.wrap(value);
 				}
 				if (!Array.isArray(value)) {
 					return value;
@@ -180,7 +192,7 @@ export class ExtHostCommands implements ExtHostCommandsShape {
 			});
 
 			try {
-				const result = await this._proxy.$executeCommand<T>(id, toArgs, retry);
+				const result = await this._proxy.$executeCommand<T>(id, hasBuffers ? new SerializableObjectWithBuffers(toArgs) : toArgs, retry);
 				return revive<any>(result);
 			} catch (e) {
 				// Rerun the command when it wasn't known, had arguments, and when retry