diff --git a/Documentation/netlink/specs/ethtool.yaml b/Documentation/netlink/specs/ethtool.yaml
index 197208f419dc..d0e4a47e0f21 100644
--- a/Documentation/netlink/specs/ethtool.yaml
+++ b/Documentation/netlink/specs/ethtool.yaml
@@ -16,6 +16,11 @@ definitions:
     name: stringset
     type: enum
     entries: []
+  -
+    name: header-flags
+    enum-name:
+    type: flags
+    entries: [ compact-bitsets, omit-reply, stats ]
 
 attribute-sets:
   -
@@ -30,6 +35,7 @@ attribute-sets:
       -
         name: flags
         type: u32
+        enum: header-flags
 
   -
     name: bitset-bit
diff --git a/tools/net/ynl/lib/ynl.py b/tools/net/ynl/lib/ynl.py
index 82d3c98067aa..b30210f537f7 100644
--- a/tools/net/ynl/lib/ynl.py
+++ b/tools/net/ynl/lib/ynl.py
@@ -100,9 +100,10 @@ class Netlink:
 class NlError(Exception):
   def __init__(self, nl_msg):
     self.nl_msg = nl_msg
+    self.error = -nl_msg.error
 
   def __str__(self):
-    return f"Netlink error: {os.strerror(-self.nl_msg.error)}\n{self.nl_msg}"
+    return f"Netlink error: {os.strerror(self.error)}\n{self.nl_msg}"
 
 
 class ConfigError(Exception):