diff --git a/source/module_relax/relax_old/test/for_test.h b/source/module_relax/relax_old/test/for_test.h
index 8ef5d2ac05..cc1597671b 100644
--- a/source/module_relax/relax_old/test/for_test.h
+++ b/source/module_relax/relax_old/test/for_test.h
@@ -68,7 +68,7 @@ UnitCell::UnitCell()
 UnitCell::~UnitCell()
 {
 }
-void UnitCell::print_tau(void) const
+void UnitCell::print_tau() const
 {
 }
 Magnetism::Magnetism()