diff --git a/contrib/pyln-proto/pyln/proto/message/message.py b/contrib/pyln-proto/pyln/proto/message/message.py
index 2f498e7ef5ef..1b8d8f37f66f 100644
--- a/contrib/pyln-proto/pyln/proto/message/message.py
+++ b/contrib/pyln-proto/pyln/proto/message/message.py
@@ -591,6 +591,8 @@ def read(namespace: MessageNamespace, io_in: BufferedIOBase) -> Optional['Messag
             fields[f.name] = f.fieldtype.read(io_in, fields)
             if fields[f.name] is None:
                 # optional fields are OK to be missing at end!
+                if f.option is not None:
+                    break
                 raise ValueError('{}: truncated at field {}'
                                  .format(mtype, f.name))
 
@@ -641,6 +643,9 @@ def write(self, io_out: BufferedIOBase) -> None:
             if f.name in self.fields:
                 val = self.fields[f.name]
             else:
+                # If this isn't present, and it's marked optional, don't write.
+                if f.option is not None:
+                    return
                 val = None
             f.fieldtype.write(io_out, val, self.fields)