diff --git a/packages/mongodb-memory-server-core/src/util/MongoBinaryDownload.ts b/packages/mongodb-memory-server-core/src/util/MongoBinaryDownload.ts
index e56e4f306..b1e6d8c8c 100644
--- a/packages/mongodb-memory-server-core/src/util/MongoBinaryDownload.ts
+++ b/packages/mongodb-memory-server-core/src/util/MongoBinaryDownload.ts
@@ -30,7 +30,7 @@ export interface MongoBinaryDownloadProgress {
  */
 export class MongoBinaryDownload {
   dlProgress: MongoBinaryDownloadProgress;
-  _downloadingUrl?: string;
+  protected _downloadingUrl?: string;
 
   /**These options are kind of raw, they are not run through DryMongoBinary.generateOptions */
   binaryOpts: Required<MongoBinaryOpts>;