diff --git a/OpenRA.Mods.Cnc/AudioLoaders/AudLoader.cs b/OpenRA.Mods.Cnc/AudioLoaders/AudLoader.cs
index 3cad70667f..5d652df4ce 100644
--- a/OpenRA.Mods.Cnc/AudioLoaders/AudLoader.cs
+++ b/OpenRA.Mods.Cnc/AudioLoaders/AudLoader.cs
@@ -24,7 +24,7 @@ namespace OpenRA.Mods.Cnc.AudioLoaders
 			var readFormat = s.ReadByte();
 			s.Position = start;
 
-			return Enum.IsDefined(typeof(SoundFormat), readFormat);
+			return readFormat == (int)SoundFormat.ImaAdpcm;
 		}
 
 		bool ISoundLoader.TryParseSound(Stream stream, out ISoundFormat sound)
diff --git a/OpenRA.Mods.Cnc/FileFormats/AudReader.cs b/OpenRA.Mods.Cnc/FileFormats/AudReader.cs
index 977df37b78..0a77c9f885 100644
--- a/OpenRA.Mods.Cnc/FileFormats/AudReader.cs
+++ b/OpenRA.Mods.Cnc/FileFormats/AudReader.cs
@@ -66,6 +66,9 @@ namespace OpenRA.Mods.Cnc.FileFormats
 				if (!Enum.IsDefined(typeof(SoundFormat), readFormat))
 					return false;
 
+				if (readFormat == (int)SoundFormat.WestwoodCompressed)
+					throw new NotImplementedException();
+
 				var offsetPosition = s.Position;
 
 				result = () =>