diff --git a/ortools/flatzinc/cp_model_fz_solver.cc b/ortools/flatzinc/cp_model_fz_solver.cc
index 3e63cc0757..541ec4d774 100644
--- a/ortools/flatzinc/cp_model_fz_solver.cc
+++ b/ortools/flatzinc/cp_model_fz_solver.cc
@@ -998,6 +998,10 @@ void SolveFzWithCpModelProto(const fz::Model& fz_model,
   }
   if (p.use_free_search) {
     m.parameters.set_search_branching(SatParameters::AUTOMATIC_SEARCH);
+    if (p.number_of_threads == 1) {
+      m.parameters.set_interleave_search(true);
+      m.parameters.set_reduce_memory_usage_in_interleave_mode(true);
+    }
   } else {
     m.parameters.set_search_branching(SatParameters::FIXED_SEARCH);
   }