diff --git a/src/vs/base/common/async.ts b/src/vs/base/common/async.ts
index e7099529bf2..9eadde4da9e 100644
--- a/src/vs/base/common/async.ts
+++ b/src/vs/base/common/async.ts
@@ -529,7 +529,7 @@ export class RunOnceScheduler {
 	 * Cancel current scheduled runner (if any).
 	 */
 	public cancel(): void {
-		if (this.timeoutToken !== -1) {
+		if (this.isScheduled()) {
 			platform.clearTimeout(this.timeoutToken);
 			this.timeoutToken = -1;
 		}
@@ -557,6 +557,13 @@ export class RunOnceScheduler {
 		this.timeoutToken = platform.setTimeout(this.timeoutHandler, this.timeout);
 	}
 
+	/**
+	 * Returns true if scheduled.
+	 */
+	public isScheduled(): boolean {
+		return this.timeoutToken !== -1;
+	}
+
 	private onTimeout() {
 		this.timeoutToken = -1;
 		if (this.runner) {