diff --git a/extensions/vscode-api-tests/src/extension.ts b/extensions/vscode-api-tests/src/extension.ts
index 162528cecea..279833c2391 100644
--- a/extensions/vscode-api-tests/src/extension.ts
+++ b/extensions/vscode-api-tests/src/extension.ts
@@ -2819,7 +2819,7 @@ export class ProtocolServer implements vscode.DebugAdapter {
 	onError: vscode.Event<Error> = this.error.event;
 
 	private sendMessage = new vscode.EventEmitter<DebugProtocol.ProtocolMessage>();
-	readonly onSendMessage: vscode.Event<DebugProtocol.ProtocolMessage> = this.sendMessage.event;
+	readonly onDidSendMessage: vscode.Event<DebugProtocol.ProtocolMessage> = this.sendMessage.event;
 
 	private _sequence: number = 1;
 	private _pendingRequests = new Map<number, (response: DebugProtocol.Response) => void>();
diff --git a/src/vs/vscode.proposed.d.ts b/src/vs/vscode.proposed.d.ts
index 36683346748..8ef405a7e4d 100644
--- a/src/vs/vscode.proposed.d.ts
+++ b/src/vs/vscode.proposed.d.ts
@@ -797,10 +797,10 @@ declare module 'vscode' {
 	export interface DebugAdapter extends Disposable {
 
 		/**
-		 * An event which fires when the debug adapter sends a Debug Adapter Protocol message to VS Code.
+		 * An event which fires after the debug adapter has sent a Debug Adapter Protocol message to VS Code.
 		 * Messages can be requests, responses, or events.
 		 */
-		readonly onSendMessage: Event<DebugProtocolMessage>;
+		readonly onDidSendMessage: Event<DebugProtocolMessage>;
 
 		/**
 		 * Handle a Debug Adapter Protocol message.
diff --git a/src/vs/workbench/api/common/extHostDebugService.ts b/src/vs/workbench/api/common/extHostDebugService.ts
index 499d4c257f7..14d70184a23 100644
--- a/src/vs/workbench/api/common/extHostDebugService.ts
+++ b/src/vs/workbench/api/common/extHostDebugService.ts
@@ -1049,8 +1049,8 @@ class DirectDebugAdapter extends AbstractDebugAdapter {
 	constructor(private implementation: vscode.DebugAdapter) {
 		super();
 
-		if (this.implementation.onSendMessage) {
-			implementation.onSendMessage((message: DebugProtocol.ProtocolMessage) => {
+		if (this.implementation.onDidSendMessage) {
+			implementation.onDidSendMessage((message: DebugProtocol.ProtocolMessage) => {
 				this.acceptMessage(message);
 			});
 		}
diff --git a/src/vs/workbench/contrib/debug/common/debug.ts b/src/vs/workbench/contrib/debug/common/debug.ts
index 06639384c6c..10118761779 100644
--- a/src/vs/workbench/contrib/debug/common/debug.ts
+++ b/src/vs/workbench/contrib/debug/common/debug.ts
@@ -548,7 +548,7 @@ export interface IDebugAdapterServer {
 }
 
 export interface IDebugAdapterInlineImpl extends IDisposable {
-	readonly onSendMessage: Event<DebugProtocol.Message>;
+	readonly onDidSendMessage: Event<DebugProtocol.Message>;
 	handleMessage(message: DebugProtocol.Message): void;
 }