diff --git a/libnetwork/internal/kvstore/kvstore.go b/libnetwork/internal/kvstore/kvstore.go
index 61ddb0777c..49e2eb9dcd 100644
--- a/libnetwork/internal/kvstore/kvstore.go
+++ b/libnetwork/internal/kvstore/kvstore.go
@@ -77,7 +77,8 @@ type Store interface {
 	// DeleteTree deletes a range of keys under a given directory
 	DeleteTree(directory string) error
 
-	// Atomic operation on a single value
+	// Atomic CAS operation on a single value.
+	// Pass previous = nil to create a new key.
 	AtomicPut(key string, value []byte, previous *KVPair, options *WriteOptions) (bool, *KVPair, error)
 
 	// Atomic delete of a single value