diff --git a/protocol/proto/spirc.proto b/protocol/proto/spirc.proto
index 1bef6e1..18fff49 100644
--- a/protocol/proto/spirc.proto
+++ b/protocol/proto/spirc.proto
@@ -66,6 +66,7 @@ enum CapabilityType {
     kIsObservable = 0x7;
     kVolumeSteps = 0x8;
     kSupportedTypes = 0x9;
+    kCommandAcks = 0xa;
 }
 
 message Goodbye {