diff --git a/src/smt/smt_parallel.cpp b/src/smt/smt_parallel.cpp
index faf45af79..fde48db95 100644
--- a/src/smt/smt_parallel.cpp
+++ b/src/smt/smt_parallel.cpp
@@ -163,7 +163,8 @@ namespace smt {
     };
 
     params_ref parallel::param_generator::apply_param_values(param_values const &pv) {
-        params_ref p = m_p;
+        params_ref p;
+        p.copy(m_p);        
         for (auto const &[k, v] : pv) {
             if (std::holds_alternative<unsigned_value>(v)) {
                 unsigned_value uv = std::get<unsigned_value>(v);