1 files changed, 2 insertions, 1 deletions
diff --git a/src/op.h b/src/op.h
index b7ae9430..ad900cc5 100644
--- a/src/op.h
+++ b/src/op.h
@@ -328,7 +328,8 @@ inline expr_t::ptr_op_t expr_t::op_t::wrap_functor(const function_t& fobj) {
 #define MAKE_FUNCTOR(x) expr_t::op_t::wrap_functor(bind(&x, this, _1))
 #define WRAP_FUNCTOR(x) expr_t::op_t::wrap_functor(x)
 
-string op_context(const expr_t::ptr_op_t op, const expr_t::ptr_op_t goal);
+string op_context(const expr_t::ptr_op_t op,
+		  const expr_t::ptr_op_t goal = NULL);
 
 } // namespace ledger