diff --git a/Documentation/netlink/specs/ethtool.yaml b/Documentation/netlink/specs/ethtool.yaml
index 1bbeaba5c6442..7d6c3ace3fa2b 100644
--- a/Documentation/netlink/specs/ethtool.yaml
+++ b/Documentation/netlink/specs/ethtool.yaml
@@ -54,6 +54,9 @@ attribute-sets:
         name: flags
         type: u32
         enum: header-flags
+      -
+        name: phy-index
+        type: u32
 
   -
     name: bitset-bit