diff --git a/extensions/ql-vscode/src/interface.ts b/extensions/ql-vscode/src/interface.ts
index a3389fdfa63..17655fa7c7c 100644
--- a/extensions/ql-vscode/src/interface.ts
+++ b/extensions/ql-vscode/src/interface.ts
@@ -399,7 +399,7 @@ export class ResultsView extends AbstractWebview<
     forceReveal: WebviewReveal,
     shouldKeepOldResultsWhileRendering = false,
   ): Promise<void> {
-    if (!fullQuery.completedQuery.successful) {
+    if (!fullQuery.completedQuery?.successful) {
       return;
     }