diff --git a/extensions/ql-vscode/package-lock.json b/extensions/ql-vscode/package-lock.json
index 269c0ea5a2a..1368aff3a8f 100644
--- a/extensions/ql-vscode/package-lock.json
+++ b/extensions/ql-vscode/package-lock.json
@@ -6461,9 +6461,9 @@
       "license": "MIT"
     },
     "node_modules/@types/node": {
-      "version": "20.17.12",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-20.17.12.tgz",
-      "integrity": "sha512-vo/wmBgMIiEA23A/knMfn/cf37VnuF52nZh5ZoW0GWt4e4sxNquibrMRJ7UQsA06+MBx9r/H1jsI9grYjQCQlw==",
+      "version": "20.17.13",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-20.17.13.tgz",
+      "integrity": "sha512-RNf+4dEeV69PIvyp++4IKM2vnLXtmp/JovfeQm5P5+qpKb6wHoH7INywLdZ7z+gVX46kgBP/fwJJvZYaHxtdyw==",
       "dev": true,
       "license": "MIT",
       "dependencies": {
diff --git a/extensions/ql-vscode/src/common/jsonl-reader.ts b/extensions/ql-vscode/src/common/jsonl-reader.ts
index fe9861aec6e..1bf1dc9b897 100644
--- a/extensions/ql-vscode/src/common/jsonl-reader.ts
+++ b/extensions/ql-vscode/src/common/jsonl-reader.ts
@@ -24,7 +24,12 @@ export async function readJsonlFile<T>(
   return new Promise((resolve, reject) => {
     const stream = createReadStream(path, { encoding: "utf8" });
     let buffer = "";
-    stream.on("data", async (chunk: string) => {
+    stream.on("data", async (chunk: string | Buffer) => {
+      if (typeof chunk !== "string") {
+        // This should never happen because we specify the encoding as "utf8".
+        throw new Error("Invalid chunk");
+      }
+
       const parts = (buffer + chunk).split(doubleLineBreakRegexp);
       buffer = parts.pop()!;
       if (parts.length > 0) {
diff --git a/extensions/ql-vscode/test/vscode-tests/no-workspace/query-results.test.ts b/extensions/ql-vscode/test/vscode-tests/no-workspace/query-results.test.ts
index 52087898d9a..a2bc725849e 100644
--- a/extensions/ql-vscode/test/vscode-tests/no-workspace/query-results.test.ts
+++ b/extensions/ql-vscode/test/vscode-tests/no-workspace/query-results.test.ts
@@ -291,7 +291,7 @@ describe("query-results", () => {
         });
 
         const finished = new Promise((res, rej) => {
-          validSarifStream.addListener("close", res);
+          validSarifStream.addListener("close", () => res(undefined));
           validSarifStream.addListener("error", rej);
         });
 
@@ -357,7 +357,7 @@ describe("query-results", () => {
         });
 
         const finished = new Promise((res, rej) => {
-          invalidSarifStream.addListener("close", res);
+          invalidSarifStream.addListener("close", () => res(undefined));
           invalidSarifStream.addListener("error", rej);
         });