diff --git a/example/box_example.cpp b/example/box_example.cpp
index 52779218..9ff5a40d 100644
--- a/example/box_example.cpp
+++ b/example/box_example.cpp
@@ -21,7 +21,6 @@
 // SOFTWARE.
 
 #include <units/format.h>
-#include <units/generic/dimensionless.h>
 #include <units/isq/mechanics.h>
 #include <units/isq/space_and_time.h>
 #include <units/si/constants.h>
diff --git a/src/core/include/units/generic/dimensionless.h b/src/core/include/units/generic/dimensionless.h
deleted file mode 100644
index da6dc0ae..00000000
--- a/src/core/include/units/generic/dimensionless.h
+++ /dev/null
@@ -1,38 +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/dimension.h>
-#include <units/unit.h>
-
-namespace units {
-
-struct dimensionless;  // defined in <units/quantity_spec.h>
-struct one;            // defined in <units/unit.h>
-
-// clang-format off
-inline constexpr struct percent : named_unit<"%", mag<ratio(1, 100)> * one> {} percent;
-inline constexpr struct per_mille : named_unit<basic_symbol_text{"‰", "%o"}, mag<ratio(1, 1000)> * one> {} per_mille;
-// clang-format on
-
-}  // namespace units
diff --git a/src/core/include/units/unit.h b/src/core/include/units/unit.h
index 89f279ba..f3d83ab3 100644
--- a/src/core/include/units/unit.h
+++ b/src/core/include/units/unit.h
@@ -398,8 +398,9 @@ struct derived_unit : detail::expr_fractions<derived_unit<>, Us...> {};
  *
  * Unit of a dimensionless quantity.
  */
-inline constexpr struct one : derived_unit<> {
-} one;
+// clang-format off
+inline constexpr struct one : derived_unit<> {} one;
+// clang-format on
 
 namespace detail {
 
@@ -721,6 +722,12 @@ inline constexpr decltype(U * U) square;
 template<Unit auto U>
 inline constexpr decltype(U * U * U) cubic;
 
+// common dimensionless units
+// clang-format off
+inline constexpr struct percent : named_unit<"%", mag<ratio{1, 100}> * one> {} percent;
+inline constexpr struct per_mille : named_unit<basic_symbol_text{"‰", "%o"}, mag<ratio(1, 1000)> * one> {} per_mille;
+// clang-format on
+
 
 // get_unit_symbol
 
diff --git a/test/unit_test/runtime/fmt_test.cpp b/test/unit_test/runtime/fmt_test.cpp
index e5efee04..d6ffa4bd 100644
--- a/test/unit_test/runtime/fmt_test.cpp
+++ b/test/unit_test/runtime/fmt_test.cpp
@@ -24,7 +24,6 @@
 #include <catch2/matchers/catch_matchers_exception.hpp>
 #include <units/customization_points.h>
 #include <units/format.h>
-#include <units/generic/dimensionless.h>
 #include <units/isq/mechanics.h>
 #include <units/isq/space_and_time.h>
 #include <units/quantity_io.h>
diff --git a/test/unit_test/static/si_test.cpp b/test/unit_test/static/si_test.cpp
index b10b987b..38b512b5 100644
--- a/test/unit_test/static/si_test.cpp
+++ b/test/unit_test/static/si_test.cpp
@@ -22,7 +22,6 @@
 
 #include <units/bits/unit_text.h>
 #include <units/generic/angle.h>
-#include <units/generic/dimensionless.h>
 #include <units/isq/si/si.h>
 
 namespace {
diff --git a/test/unit_test/static/unit_test.cpp b/test/unit_test/static/unit_test.cpp
index a69cb765..f5bc7b9e 100644
--- a/test/unit_test/static/unit_test.cpp
+++ b/test/unit_test/static/unit_test.cpp
@@ -22,7 +22,6 @@
 
 #include "test_tools.h"
 #include <units/dimension.h>
-#include <units/generic/dimensionless.h>
 #include <units/reference.h>
 #include <units/si/prefixes.h>
 #include <units/unit.h>