diff --git a/src/muz/rel/dl_mk_simple_joins.cpp b/src/muz/rel/dl_mk_simple_joins.cpp
index 87ec378ea..9606c229e 100644
--- a/src/muz/rel/dl_mk_simple_joins.cpp
+++ b/src/muz/rel/dl_mk_simple_joins.cpp
@@ -377,7 +377,7 @@ namespace datalog {
             }
 
             func_decl * decl = m_context.mk_fresh_head_predicate(
-                symbol(parent_name.c_str()), symbol("split"), 
+                symbol(parent_name), symbol("split"), 
                 arity, domain.c_ptr(), parent_head);
 
             app_ref head(m.mk_app(decl, arity, args.c_ptr()), m);