diff --git a/FFMpegCore.Test/ArgumentBuilderTest.cs b/FFMpegCore.Test/ArgumentBuilderTest.cs
index d70e8a9..8dbe641 100644
--- a/FFMpegCore.Test/ArgumentBuilderTest.cs
+++ b/FFMpegCore.Test/ArgumentBuilderTest.cs
@@ -94,7 +94,7 @@ public void Builder_BuildString_Quiet()
         [TestMethod]
         public void Builder_BuildString_AudioCodec_Fluent()
         {
-            var str = GetArgumentsString(new ArgumentContainer().AudioCodec(AudioCodec.Aac));
+            var str = GetArgumentsString(new ArgumentContainer().AudioCodec(AudioCodec.Aac).AudioBitrate(128));
             Assert.AreEqual(str, "-i \"input.mp4\" -c:a aac -b:a 128k \"output.mp4\"");
         }
 
diff --git a/FFMpegCore.Test/Resources/input.webm b/FFMpegCore.Test/Resources/input.webm
new file mode 100644
index 0000000..478b68a
Binary files /dev/null and b/FFMpegCore.Test/Resources/input.webm differ