diff --git a/src/conf/cards/RME9636.conf b/src/conf/cards/RME9636.conf
index 3db270c3..d45c1b28 100644
--- a/src/conf/cards/RME9636.conf
+++ b/src/conf/cards/RME9636.conf
@@ -53,6 +53,7 @@ RME9636.pcm.iec958.0 {
 		type ctl_elems
 		hook_args [
 			{
+				interface PCM
 				name "IEC958 Playback PCM Stream"
 				lock true
 				value [ $AES0 $AES1 $AES2 $AES3 ]