diff --git a/devine/core/drm/widevine.py b/devine/core/drm/widevine.py
index 90af853..b391e05 100644
--- a/devine/core/drm/widevine.py
+++ b/devine/core/drm/widevine.py
@@ -235,7 +235,7 @@ class Widevine:
 
         try:
             arguments = [
-                f"input={path},stream=0,output={output_path}",
+                f"input={path},stream=0,output={output_path},output_format=MP4",
                 "--enable_raw_key_decryption", "--keys",
                 ",".join([
                     *[