diff --git a/tools/topology/topology2/include/common/pcm.conf b/tools/topology/topology2/include/common/pcm.conf
index 01e9358bf758..ba014d084bee 100644
--- a/tools/topology/topology2/include/common/pcm.conf
+++ b/tools/topology/topology2/include/common/pcm.conf
@@ -25,9 +25,9 @@ Class.PCM."pcm" {
 	DefineAttribute."direction" {
 		constraints {
 			!valid_values [
-				playback
-				capture
-				duplex
+				"playback"
+				"capture"
+				"duplex"
 			]
 		}
 	}