diff --git a/src/include/units/constant.h b/src/include/units/constant.h
deleted file mode 100644
index 8e97e0d7..00000000
--- a/src/include/units/constant.h
+++ /dev/null
@@ -1,46 +0,0 @@
-
-// The MIT License (MIT)
-//
-// Copyright (c) 2018 Mateusz Pusz
-//
-// Permission is hereby granted, free of charge, to any person obtaining a copy
-// of this software and associated documentation files (the "Software"), to deal
-// in the Software without restriction, including without limitation the rights
-// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-// copies of the Software, and to permit persons to whom the Software is
-// furnished to do so, subject to the following conditions:
-//
-// The above copyright notice and this permission notice shall be included in all
-// copies or substantial portions of the Software.
-//
-// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-// SOFTWARE.
-
-#pragma once
-
-#include <units/quantity.h>
-
-
-namespace units {
-
-namespace detail {
-
-template<Ratio R, Exponent... Es>
-struct constant_helper {
-  using dim = downcast_dimension<typename detail::make_dimension<Es...>>;
-  using ratio = ratio_multiply<R, typename dimension_unit<dim>::ratio>;
-  using unit = downcast_unit<dim, R>;
-  static constexpr quantity<dim, unit> value{1};
-};
-
-}
-
-template<Ratio R, Exponent E, Exponent... Rest>
-inline constexpr auto constant = detail::constant_helper<R, E, Rest...>::value;
-
-}  // namespace units
diff --git a/src/include/units/physical/si/constants.h b/src/include/units/physical/si/constants.h
index 0530746b..3ce34bd3 100644
--- a/src/include/units/physical/si/constants.h
+++ b/src/include/units/physical/si/constants.h
@@ -22,7 +22,6 @@
 
 #pragma once
 
-#include <units/constant.h>
 #include <units/physical/si/electric_charge.h>
 #include <units/physical/si/frequency.h>
 #include <units/physical/si/energy.h>
@@ -33,13 +32,13 @@
 
 namespace units::si {
 
-inline constexpr auto planck_constant = constant<ratio<662607015, 1, -42>, exp<dim_energy, 1>, exp<dim_time, 1>>;
-inline constexpr auto elementary_charge = constant<ratio<1602176634, 1, -51>, exp<dim_electric_charge, 1>>;
-inline constexpr auto boltzmann_constant =
-    constant<ratio<1380649, 1, -29>, exp<dim_energy, 1>, exp<dim_thermodynamic_temperature, -1>>;
-inline constexpr auto avogadro_constant = constant<ratio<602214076, 1, 15>, exp<dim_substance, -1>>;
-inline constexpr auto speed_of_light = constant<ratio<299792458, 1, 15>, exp<dim_velocity, 1>>;
-inline constexpr auto hyperfine_structure_transition_frequency = constant<ratio<9192631770>, exp<dim_frequency, 1>>;
-// inline constexpr auto luminous_efficacy = constant<ratio<683>, exp<luminous_flux, 1>, exp<power, -1>>;
+inline constexpr auto planck_constant = 6.62607015e-34q_J * 1q_s;
+inline constexpr auto reduced_planck_constant = 6.582119569e-10q_GeV * 1q_s;
+inline constexpr auto elementary_charge = 1.602176634e-19q_C;
+inline constexpr auto boltzmann_constant = 1.380649e-23q_J / 1q_K;
+inline constexpr auto avogadro_constant = 6.02214076e23 / 1q_mol;
+inline constexpr auto speed_of_light = 299792458q_mps;
+inline constexpr auto hyperfine_structure_transition_frequency = 9192631770q_Hz;
+// inline constexpr auto luminous_efficacy = 683q_lm / 1q_W;
 
 }  // namespace units::si