diff --git a/src/per-language-bundles.test.ts b/src/per-language-bundles.test.ts
index b8f48512fe..0330b51a63 100644
--- a/src/per-language-bundles.test.ts
+++ b/src/per-language-bundles.test.ts
@@ -38,7 +38,6 @@ async function checkEligibility(
         [ActionsEnvVars.RUNNER_ENVIRONMENT]: "github-hosted",
       }),
       features: createFeatures([Feature.PerLanguageBundles]),
-      logger: getRecordingLogger([], { logToConsole: false }),
       ...stateOverrides,
     }),
     { ...ELIGIBLE_OPTIONS, ...overrides },
@@ -134,7 +133,6 @@ test("getPerLanguageBundleLanguage explains a disabled feature before checking e
   const messages: LoggedMessage[] = [];
   const language = await getPerLanguageBundleLanguage(
     initAllState({
-      env: getTestEnv(),
       features: createFeatures([]),
       logger: getRecordingLogger(messages, { logToConsole: false }),
     }),
diff --git a/src/per-language-bundles.ts b/src/per-language-bundles.ts
index f4e46403db..e4468d2f34 100644
--- a/src/per-language-bundles.ts
+++ b/src/per-language-bundles.ts
@@ -102,8 +102,11 @@ export async function getPerLanguageBundleLanguage(
     return explain("the job is not running on a GitHub-hosted runner");
   }
 
-  // Check whether per-language bundles are published for the requested CLI version.
-  // Latest-nightly selection skips this release-version check, but not the other eligibility checks.
+  // Nightly releases are identified by dates rather than versions. If
+  // `isLatestNightly` is `true`, the latest nightly is requested with
+  // `tools: nightly` and we don't yet have the corresponding tag at this point.
+  // Therefore, we skip the version check and don't have an equivalent.
+  // We can safely assume that the latest nightly will have per-language bundles.
   if (!isLatestNightly) {
     if (cliVersion === undefined) {
       return explain("the requested CLI version is unknown");
diff --git a/src/setup-codeql.test.ts b/src/setup-codeql.test.ts
index c35bdb8406..6ac5bebf18 100644
--- a/src/setup-codeql.test.ts
+++ b/src/setup-codeql.test.ts
@@ -69,25 +69,29 @@ function stubHostedNightly(tagName: string) {
     available: true,
     foundZstdBinary: true,
   });
-  const fetchRelease = sinon
-    .stub<Parameters<typeof fetch>, ReturnType<typeof fetch>>()
-    .rejects(new Error("Unexpected API request in nightly bundle test"));
-  fetchRelease
-    .withArgs(
-      "https://api.github.com/repos/dsp-testing/codeql-cli-nightlies/releases?per_page=1&page=1&prerelease=true",
-      sinon.match({ method: "GET" }),
-    )
-    .callsFake(
-      async () =>
-        new Response(JSON.stringify([{ tag_name: tagName }]), {
-          headers: { "content-type": "application/json" },
-        }),
-    );
   const client = github.getOctokit("123", {
-    request: { fetch: fetchRelease },
+    request: {
+      fetch: async () => {
+        throw new Error("Unexpected API request in nightly bundle test");
+      },
+    },
   });
+  const listReleases = sinon
+    .stub(client.rest.repos, "listReleases")
+    .rejects(new Error("Unexpected release request in nightly bundle test"));
+  listReleases
+    .withArgs({
+      owner: "dsp-testing",
+      repo: "codeql-cli-nightlies",
+      per_page: 1,
+      page: 1,
+      prerelease: true,
+    })
+    .resolves({
+      data: [{ tag_name: tagName }],
+    } as Awaited<ReturnType<typeof client.rest.repos.listReleases>>);
   sinon.stub(api, "getApiClient").value(() => client);
-  return fetchRelease;
+  return listReleases;
 }
 
 test.serial("parse codeql bundle url version", (t) => {
diff --git a/src/util.ts b/src/util.ts
index 456cd7c3d2..d74e07fa8d 100644
--- a/src/util.ts
+++ b/src/util.ts
@@ -682,7 +682,7 @@ export async function bundleDb(
   return databaseBundlePath;
 }
 
-/** Returns the elapsed milliseconds, rounded, since a `performance.now()` timestamp. */
+/** Returns the elapsed milliseconds, rounded, since `startTime` was recorded with `performance.now()`. */
 export function durationMsSince(startTime: number): number {
   return Math.round(performance.now() - startTime);
 }