diff --git a/src/main.ts b/src/main.ts
index 88992f2..77e11d1 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -80,8 +80,8 @@ const reduceSize = (file: string, bitrate: number) => {
   const finalFile = getNewFilename(file, "Compressed - ");
 
   child_process.execSync(
-    `${ffmpegPath} -y -i "${file}" -c:v libx264 -b:v ${videoBitrate}k -pass 1 -an -f null ${nul} && \
-     ${ffmpegPath} -y -i "${file}" -c:v libx264 -b:v ${videoBitrate}k -pass 2 -c:a copy -map 0:0 -map 0:1 -map 0:2 -map 0:3 "${finalFile}"`
+    `${ffmpegPath} -y -i "${file}" -c:v libx264 -b:v ${videoBitrate}k -pass 1 -an -f mp4 ${nul} && \
+     ${ffmpegPath} -y -i "${file}" -c:v libx264 -b:v ${videoBitrate}k -pass 2 -c:a copy -map 0:0 -map 0:1 -map 0:2 -map 0:3 -f mp4 "${finalFile}"`
   );
 
   // Delete the old file