diff --git a/src/vs/workbench/api/common/extHost.protocol.ts b/src/vs/workbench/api/common/extHost.protocol.ts
index f1a029ec55f2fe7b5f4eb5a405b7518c649b27e5..d34babb11c3e485691feef1381cf6dd1d25e89a3 100644
--- a/src/vs/workbench/api/common/extHost.protocol.ts
+++ b/src/vs/workbench/api/common/extHost.protocol.ts
@@ -54,6 +54,7 @@ import { revive } from 'vs/base/common/marshalling';
 import { INotebookMimeTypeSelector, IOutput, INotebookDisplayOrder, NotebookCellMetadata, NotebookDocumentMetadata } from 'vs/workbench/contrib/notebook/common/notebookCommon';
 import { CallHierarchyItem } from 'vs/workbench/contrib/callHierarchy/common/callHierarchy';
 import { Dto } from 'vs/base/common/types';
+import { EnvironmentVariableMutatorType } from 'vs/workbench/contrib/terminal/common/environmentVariable';
 
 export interface IEnvironment {
 	isExtensionDevelopmentDebug: boolean;
@@ -426,12 +427,6 @@ export interface TerminalLaunchConfig {
 	isExtensionTerminal?: boolean;
 }
 
-export enum EnvironmentVariableMutatorType {
-	Replace = 1,
-	Append = 2,
-	Prepend = 3
-}
-
 export interface IEnvironmentVariableCollectionDto {
 	extensionIdentifier: string;
 	variables: string[];
diff --git a/src/vs/workbench/api/common/extHostTerminalService.ts b/src/vs/workbench/api/common/extHostTerminalService.ts
index b332a4e5cde91f315b49405d01b54d430e1c6aa9..3f150634ab7149fdec3f44b6ab840e411bf8c539 100644
--- a/src/vs/workbench/api/common/extHostTerminalService.ts
+++ b/src/vs/workbench/api/common/extHostTerminalService.ts
@@ -674,6 +674,7 @@ export class WorkerExtHostTerminalService extends BaseExtHostTerminalService {
 	}
 
 	public getEnvironmentVariableCollection(extension: IExtensionDescription, persistent?: boolean): vscode.EnvironmentVariableCollection {
+		// This is not implemented so worker ext host extensions cannot influence terminal envs
 		throw new Error('Not implemented');
 	}
 }
diff --git a/src/vs/workbench/api/node/extHostTerminalService.ts b/src/vs/workbench/api/node/extHostTerminalService.ts
index ae78dfb7b78c23e4d7cbfd8879a3e0b5955b3003..3d64ebc8f5ae84918fccce66d709fafa00de5675 100644
--- a/src/vs/workbench/api/node/extHostTerminalService.ts
+++ b/src/vs/workbench/api/node/extHostTerminalService.ts
@@ -9,7 +9,7 @@ import * as os from 'os';
 import { URI, UriComponents } from 'vs/base/common/uri';
 import * as platform from 'vs/base/common/platform';
 import * as terminalEnvironment from 'vs/workbench/contrib/terminal/common/terminalEnvironment';
-import { IShellLaunchConfigDto, IShellDefinitionDto, IShellAndArgsDto } from 'vs/workbench/api/common/extHost.protocol';
+import { IShellLaunchConfigDto, IShellDefinitionDto, IShellAndArgsDto, IEnvironmentVariableCollectionDto } from 'vs/workbench/api/common/extHost.protocol';
 import { ExtHostConfiguration, ExtHostConfigProvider, IExtHostConfiguration } from 'vs/workbench/api/common/extHostConfiguration';
 import { ILogService } from 'vs/platform/log/common/log';
 import { IShellLaunchConfig, ITerminalEnvironment } from 'vs/workbench/contrib/terminal/common/terminal';
@@ -287,13 +287,35 @@ export class ExtHostTerminalService extends BaseExtHostTerminalService {
 		} else {
 			collection = new EnvironmentVariableCollection();
 		}
-		collection.onDidChangeCollection(() => this._updateEnvironmentVariableCollection());
+		collection.onDidChangeCollection(() => this._updateEnvironmentVariableCollections());
 		this._environmentVariableCollection.set(extension.identifier.value, collection);
 		return collection;
 	}
 
 	@debounce(1000)
-	private _updateEnvironmentVariableCollection() {
+	private _updateEnvironmentVariableCollections(): void {
+		const dtos: IEnvironmentVariableCollectionDto[] = [];
+		this._environmentVariableCollection.forEach((collection, extensionIdenfitier) => {
+			dtos.push(this._serializeEnvironmentVariableCollection(extensionIdenfitier, collection));
+		});
+
 		// TODO: Send updates back to renderer
 	}
+
+	private _serializeEnvironmentVariableCollection(extensionIdentifier: string, collection: vscode.EnvironmentVariableCollection): IEnvironmentVariableCollectionDto {
+		const variables: string[] = [];
+		const values: string[] = [];
+		const types: EnvironmentVariableMutatorType[] = [];
+		collection.forEach((variable, mutator) => {
+			variables.push(variable);
+			values.push(mutator.value);
+			types.push(mutator.type);
+		});
+		return {
+			extensionIdentifier,
+			variables,
+			values,
+			types
+		};
+	}
 }
diff --git a/src/vs/workbench/contrib/terminal/common/environmentVariable.ts b/src/vs/workbench/contrib/terminal/common/environmentVariable.ts
index d513a3f6588c01f66a8326b760b613a2bdaf1168..4cbfcf4d43dd9a04c74d0ed5a0473f6345f061d1 100644
--- a/src/vs/workbench/contrib/terminal/common/environmentVariable.ts
+++ b/src/vs/workbench/contrib/terminal/common/environmentVariable.ts
@@ -7,9 +7,15 @@ import { createDecorator } from 'vs/platform/instantiation/common/instantiation'
 
 export const IEnvironmentVariableService = createDecorator<IEnvironmentVariableService>('environmentVariableService');
 
+export enum EnvironmentVariableMutatorType {
+	Replace = 1,
+	Append = 2,
+	Prepend = 3
+}
+
 export interface IEnvironmentVariableMutator {
 	readonly value: string;
-	readonly type: 'replace' | 'append' | 'prepend';
+	readonly type: EnvironmentVariableMutatorType;
 }
 
 export interface IEnvironmentVariableCollection {