diff --git a/src/main/downloadsManager.test.js b/src/main/downloadsManager.test.js
index d44c23737c2..8f556e152be 100644
--- a/src/main/downloadsManager.test.js
+++ b/src/main/downloadsManager.test.js
@@ -192,6 +192,20 @@ describe('main/downloadsManager', () => {
         expect(dl.fileSizes.get('file.txt')).toBe('4242');
     });
 
+    it('MM-68690 - should not throw when content-disposition header is missing', () => {
+        const dl = new DownloadsManager({});
+        const details = {
+            responseHeaders: {
+                'content-encoding': ['gzip'],
+                'x-uncompressed-content-length': ['4242'],
+            },
+        };
+        const cb = jest.fn();
+        expect(() => dl.webRequestOnHeadersReceivedHandler(details, cb)).not.toThrow();
+        expect(cb).toHaveBeenCalledWith({});
+        expect(dl.fileSizes.size).toBe(0);
+    });
+
     it('should clear the downloads list', () => {
         const dl = new DownloadsManager(JSON.stringify(downloadsJson));
         dl.clearDownloadsDropDown();
diff --git a/src/main/downloadsManager.ts b/src/main/downloadsManager.ts
index 2de8b52d38f..d853c0593fa 100644
--- a/src/main/downloadsManager.ts
+++ b/src/main/downloadsManager.ts
@@ -143,7 +143,7 @@ export class DownloadsManager extends JsonFileManager<DownloadedItems> {
     webRequestOnHeadersReceivedHandler = (details: Electron.OnHeadersReceivedListenerDetails, cb: (headersReceivedResponse: Electron.HeadersReceivedResponse) => void) => {
         const headers = details.responseHeaders ?? {};
 
-        if (headers?.['content-encoding']?.includes('gzip') && headers?.['x-uncompressed-content-length'] && headers?.['content-disposition'].join(';')?.includes('filename=')) {
+        if (headers?.['content-encoding']?.includes('gzip') && headers?.['x-uncompressed-content-length'] && headers?.['content-disposition']?.join?.(';')?.includes('filename=')) {
             const filename = readFilenameFromContentDispositionHeader(headers['content-disposition']);
             const fileSize = headers['x-uncompressed-content-length']?.[0] || '0';
             if (filename && (!this.fileSizes.has(filename) || this.fileSizes.get(filename)?.toString() !== fileSize)) {