diff --git a/test/unit_test/static/quantity_test.cpp b/test/unit_test/static/quantity_test.cpp
index c267c50f..b49dc113 100644
--- a/test/unit_test/static/quantity_test.cpp
+++ b/test/unit_test/static/quantity_test.cpp
@@ -299,7 +299,7 @@ static_assert(dimensionless<unitless>(1) + 1 == 2);
 static_assert(dimensionless<unitless, int>(1) + 1 == 2);
 
 template<typename Rep>
-concept invalid_dimensionless_operation = requires()
+concept invalid_dimensionless_operation = requires
 {
     !requires(dimensionless<unitless, Rep> d) { d + 1.23; };
     !requires(dimensionless<unitless, Rep> d) { 1.23 + d; };