diff --git a/src/director/packs/packs.test.mjs b/src/director/packs/packs.test.mjs
index 036f31c02..f31d65090 100644
--- a/src/director/packs/packs.test.mjs
+++ b/src/director/packs/packs.test.mjs
@@ -338,3 +338,28 @@ test('byte and integrity checks run before rendering; adapter names never resolv
   assert.equal(mounted, 1);
   session.destroy();
 });
+
+test('failed responses release their body and an already-cancelled source sends no request', async () => {
+  let cancelled = 0,
+    requests = 0;
+  const source = createAssetDirectorySource({
+    baseUrl: 'https://example.org/packs/',
+    fetchImpl: async () => {
+      requests++;
+      return new Response(
+        new ReadableStream({
+          cancel() {
+            cancelled++;
+          },
+        }),
+        { status: 403 },
+      );
+    },
+  });
+  await assert.rejects(source({ path: 'a.json' }), /unavailable/);
+  assert.equal(cancelled, 1);
+  const controller = new AbortController();
+  controller.abort();
+  await assert.rejects(source({ path: 'a.json', signal: controller.signal }));
+  assert.equal(requests, 1);
+});
diff --git a/src/director/packs/source.js b/src/director/packs/source.js
index 50f4d2e53..4828827af 100644
--- a/src/director/packs/source.js
+++ b/src/director/packs/source.js
@@ -19,6 +19,7 @@ export function createAssetDirectorySource({
     );
   return async ({ path, signal, maxBytes = PACK_LIMITS.bytes }) => {
     validateAssetPath(path);
+    signal?.throwIfAborted();
     const response = await fetchImpl(new URL(path, base).href, {
       signal,
       credentials: 'omit',
@@ -26,7 +27,10 @@ export function createAssetDirectorySource({
       referrerPolicy: 'no-referrer',
       cache: 'no-store',
     });
-    if (!response.ok) throw new Error('Asset unavailable');
+    if (!response.ok) {
+      await response.body?.cancel().catch(() => {});
+      throw new Error('Asset unavailable');
+    }
     const reader = response.body?.getReader();
     if (!reader) throw new Error('Asset stream unavailable');
     const chunks = [];