diff --git a/src/ThumbnailApi.ts b/src/ThumbnailApi.ts
index 370dd14..35c2404 100644
--- a/src/ThumbnailApi.ts
+++ b/src/ThumbnailApi.ts
@@ -98,6 +98,7 @@ export class ThumbnailApi {
 
     if (!this.responseHelper.okStatus(status)) {
       const error = new Error(`Status ${String(status)} from upstream.`);
+      this.releaseUpstreamBody(remoteImageResponse);
       this.sendError(expressResponse, itemId, 404, error);
       return;
     }
@@ -106,6 +107,7 @@ export class ThumbnailApi {
 
     if (!this.responseHelper.okHeaders(remoteImageResponse.headers)) {
       const error = new Error(`Got bad headers from upstream.`);
+      this.releaseUpstreamBody(remoteImageResponse);
       this.sendError(expressResponse, itemId, 404, error);
       return;
     }
@@ -139,6 +141,7 @@ export class ThumbnailApi {
 
     if (!this.responseHelper.okStatus(status)) {
       const error = new Error(`Status ${String(status)} from upstream.`);
+      this.releaseUpstreamBody(response);
       this.sendError(expressResponse, itemId, 404, error);
       return;
     }
@@ -169,6 +172,10 @@ export class ThumbnailApi {
     }
   }
 
+  private releaseUpstreamBody(response: Response): void {
+    void response.body?.cancel?.()?.catch(() => {});
+  }
+
   sendError(
     res: express.Response,
     itemId: string,