diff --git a/src/runtime/c/pgf/pgf.h b/src/runtime/c/pgf/pgf.h
index 4e89f541e..fbb26d187 100644
--- a/src/runtime/c/pgf/pgf.h
+++ b/src/runtime/c/pgf/pgf.h
@@ -203,9 +203,9 @@ struct PgfUnmarshaller {
 typedef struct PgfMarshaller PgfMarshaller;
 typedef struct PgfMarshallerVtbl PgfMarshallerVtbl;
 struct PgfMarshallerVtbl {
-    object (*match_lit)(PgfUnmarshaller *u, PgfLiteral lit);
-    object (*match_expr)(PgfUnmarshaller *u, PgfExpr expr);
-    object (*match_type)(PgfUnmarshaller *u, PgfType ty);
+    object (*match_lit)(PgfMarshaller *this, PgfUnmarshaller *u, PgfLiteral lit);
+    object (*match_expr)(PgfMarshaller *this, PgfUnmarshaller *u, PgfExpr expr);
+    object (*match_type)(PgfMarshaller *this, PgfUnmarshaller *u, PgfType ty);
 };
 struct PgfMarshaller {
     PgfMarshallerVtbl *vtbl;
diff --git a/src/runtime/python/marshaller.c b/src/runtime/python/marshaller.c
index c5f575a9c..426ff8c5e 100644
--- a/src/runtime/python/marshaller.c
+++ b/src/runtime/python/marshaller.c
@@ -180,7 +180,7 @@ PyString_AsPgfText(PyObject *pystr)
 
 // ----------------------------------------------------------------------------
 
-object match_lit(PgfUnmarshaller *u, PgfLiteral lit)
+object match_lit(PgfMarshaller *this, PgfUnmarshaller *u, PgfLiteral lit)
 {
     PyObject *pyobj = (PyObject *)lit;
 
@@ -200,13 +200,13 @@ object match_lit(PgfUnmarshaller *u, PgfLiteral lit)
     }
 }
 
-object match_expr(PgfUnmarshaller *u, PgfExpr expr)
+object match_expr(PgfMarshaller *this, PgfUnmarshaller *u, PgfExpr expr)
 {
     PyErr_SetString(PyExc_NotImplementedError, "match_expr not implemented");
     Py_RETURN_NOTIMPLEMENTED;
 }
 
-object match_type(PgfUnmarshaller *u, PgfType ty)
+object match_type(PgfMarshaller *this, PgfUnmarshaller *u, PgfType ty)
 {
     TypeObject *type = (TypeObject *)ty;