diff --git a/test/unit_test/static/unit_test.cpp b/test/unit_test/static/unit_test.cpp
index 29524d82..6c188b52 100644
--- a/test/unit_test/static/unit_test.cpp
+++ b/test/unit_test/static/unit_test.cpp
@@ -83,7 +83,7 @@ inline constexpr struct kilojoule_ : decltype(si::kilo<joule>) {} kilojoule;
 
 // physical constant units
 inline constexpr struct standard_gravity_unit_ : constant_unit<"g", mag<ratio{980'665, 100'000}> * metre / square<second>> {} standard_gravity_unit;
-inline constexpr struct speed_of_light_unit_ : constant_unit<"c", mag<299'792'458> * metre / second> {} speed_of_light_unit;
+inline constexpr struct speed_of_light_in_vacuum_unit_ : constant_unit<"c", mag<299'792'458> * metre / second> {} speed_of_light_in_vacuum_unit;
 
 // clang-format on
 
@@ -329,10 +329,10 @@ static_assert(is_of_type<gram * standard_gravity_unit, derived_unit<standard_gra
 static_assert(is_of_type<standard_gravity_unit / gram, derived_unit<standard_gravity_unit_, per<gram_>>>);
 static_assert(is_of_type<gram / standard_gravity_unit, derived_unit<gram_, per<standard_gravity_unit_>>>);
 static_assert(is_of_type<standard_gravity_unit * gram / standard_gravity_unit, gram_>);
-static_assert(is_of_type<speed_of_light_unit * gram * standard_gravity_unit,
-                         derived_unit<speed_of_light_unit_, standard_gravity_unit_, gram_>>);
-static_assert(is_of_type<gram * standard_gravity_unit * speed_of_light_unit,
-                         derived_unit<speed_of_light_unit_, standard_gravity_unit_, gram_>>);
+static_assert(is_of_type<speed_of_light_in_vacuum_unit * gram * standard_gravity_unit,
+                         derived_unit<speed_of_light_in_vacuum_unit_, standard_gravity_unit_, gram_>>);
+static_assert(is_of_type<gram * standard_gravity_unit * speed_of_light_in_vacuum_unit,
+                         derived_unit<speed_of_light_in_vacuum_unit_, standard_gravity_unit_, gram_>>);
 
 static_assert(std::is_same_v<decltype(1 / second * metre), decltype(metre / second)>);
 static_assert(std::is_same_v<decltype(metre * (1 / second)), decltype(metre / second)>);
@@ -369,7 +369,7 @@ static_assert(
 static_assert(get_canonical_unit(standard_gravity_unit).mag == mag<ratio{980'665, 100'000}>);
 static_assert(is_of_type<get_canonical_unit(standard_gravity_unit* gram).reference_unit,
                          derived_unit<gram_, metre_, per<power<second_, 2>>>>);
-static_assert(is_of_type<get_canonical_unit(standard_gravity_unit / speed_of_light_unit).reference_unit,
+static_assert(is_of_type<get_canonical_unit(standard_gravity_unit / speed_of_light_in_vacuum_unit).reference_unit,
                          derived_unit<one_, per<second_>>>);
 
 // operations commutativity
@@ -530,7 +530,8 @@ static_assert(is_of_type<detail::common_unit(metre / second, kilometre / hour),
                          scaled_unit<mag<ratio{1, 18}>, derived_unit<metre_, per<second_>>>>);
 static_assert(is_of_type<detail::common_unit(kilometre, mile), scaled_unit<mag<ratio{8, 125}>, metre_>>);
 static_assert(is_of_type<detail::common_unit(mile, kilometre), scaled_unit<mag<ratio{8, 125}>, metre_>>);
-static_assert(is_of_type<detail::common_unit(speed_of_light_unit, metre / second), derived_unit<metre_, per<second_>>>);
+static_assert(
+  is_of_type<detail::common_unit(speed_of_light_in_vacuum_unit, metre / second), derived_unit<metre_, per<second_>>>);
 
 // unit symbols
 #ifdef __cpp_lib_constexpr_string
@@ -607,8 +608,8 @@ static_assert(unit_symbol(pow<3, 5>(metre)) == "m^(3/5)");
 static_assert(unit_symbol(pow<1, 2>(metre / second)) == "m^(1/2)/s^(1/2)");
 
 // Physical constants
-static_assert(unit_symbol(speed_of_light_unit) == "[c]");
-static_assert(unit_symbol(gram * standard_gravity_unit * speed_of_light_unit) == "[c] [g] g");
+static_assert(unit_symbol(speed_of_light_in_vacuum_unit) == "[c]");
+static_assert(unit_symbol(gram * standard_gravity_unit * speed_of_light_in_vacuum_unit) == "[c] [g] g");
 static_assert(unit_symbol(gram / standard_gravity_unit) == "g/[g]");
 
 #endif  // __cpp_lib_constexpr_string