diff --git a/packages/core/src/internal/fetchSource.ts b/packages/core/src/internal/fetchSource.ts
index b97d943229..3981687337 100644
--- a/packages/core/src/internal/fetchSource.ts
+++ b/packages/core/src/internal/fetchSource.ts
@@ -22,6 +22,7 @@ async function* streamBody(response: Response): AsyncIterableIterator<string> {
     const reader = response.body!.getReader();
     let result: ReadableStreamReadResult<ChunkData>;
     while (!(result = await reader.read()).done) yield toString(result.value);
+    await reader.cancel();
   }
 }