diff --git a/source/core/Ky.ts b/source/core/Ky.ts
index 5218d6c7..4839bfed 100644
--- a/source/core/Ky.ts
+++ b/source/core/Ky.ts
@@ -35,6 +35,8 @@ export class Ky {
 
 			// Delay the fetch so that body method shortcuts can set the Accept header
 			await Promise.resolve();
+			// Before using ky.request, _fetch clones it and saves the clone for future retries to use.
+			// If retry is not needed, close the cloned request's ReadableStream for memory safety.
 			let response = await ky._fetch();
 
 			for (const hook of ky._options.hooks.afterResponse) {
@@ -63,6 +65,11 @@ export class Ky {
 				throw error;
 			}
 
+			// Now that we know a retry is not needed, close the ReadableStream of the cloned request.
+			if (!ky.request.bodyUsed) {
+				await ky.request.body?.cancel();
+			}
+
 			// If `onDownloadProgress` is passed, it uses the stream API internally
 			/* istanbul ignore next */
 			if (ky._options.onDownloadProgress) {