diff --git a/FFMpegCore.Test/ArgumentBuilderTest.cs b/FFMpegCore.Test/ArgumentBuilderTest.cs
index 9cf7e39..906a87b 100644
--- a/FFMpegCore.Test/ArgumentBuilderTest.cs
+++ b/FFMpegCore.Test/ArgumentBuilderTest.cs
@@ -114,7 +114,7 @@ public void Builder_BuildString_Copy_Both()
         {
             var str = FFMpegArguments.FromFileInput("input.mp4")
                 .OutputToFile("output.mp4", false, opt => opt.CopyChannel()).Arguments;
-            Assert.AreEqual("-i \"input.mp4\" -c copy \"output.mp4\"", str);
+            Assert.AreEqual("-i \"input.mp4\" -c:a copy -c:v copy \"output.mp4\"", str);
         }
 
         [TestMethod]