diff --git a/src/vs/workbench/api/node/extHostTerminalService.ts b/src/vs/workbench/api/node/extHostTerminalService.ts
index a45253a3a3b12e164b12f39fb2cd8fe4735d3b64..259902c99899ec6b66ac51d661b48e45a6ed6e4f 100644
--- a/src/vs/workbench/api/node/extHostTerminalService.ts
+++ b/src/vs/workbench/api/node/extHostTerminalService.ts
@@ -455,7 +455,7 @@ export class ExtHostTerminalService implements ExtHostTerminalServiceShape {
 		return this._getTerminalPromises[id];
 	}
 
-	private _delay(timeout: number, result: any) {
+	private _delay(timeout: number, result: any): Promise<void> {
 		return new Promise(c => {
 			setTimeout(c(result), timeout);
 		});