diff --git a/include/nlohmann/detail/conversions/from_json.hpp b/include/nlohmann/detail/conversions/from_json.hpp
index 224fb33f9..b24643b0e 100644
--- a/include/nlohmann/detail/conversions/from_json.hpp
+++ b/include/nlohmann/detail/conversions/from_json.hpp
@@ -2,7 +2,6 @@
 
 #include <algorithm> // transform
 #include <array> // array
-#include <ciso646> // and, not
 #include <forward_list> // forward_list
 #include <iterator> // inserter, front_inserter, end
 #include <map> // map
diff --git a/include/nlohmann/detail/conversions/to_chars.hpp b/include/nlohmann/detail/conversions/to_chars.hpp
index feafaec84..86c89f3a3 100644
--- a/include/nlohmann/detail/conversions/to_chars.hpp
+++ b/include/nlohmann/detail/conversions/to_chars.hpp
@@ -2,7 +2,6 @@
 
 #include <array> // array
 #include <cassert> // assert
-#include <ciso646> // or, and, not
 #include <cmath>   // signbit, isfinite
 #include <cstdint> // intN_t, uintN_t
 #include <cstring> // memcpy, memmove
diff --git a/include/nlohmann/detail/conversions/to_json.hpp b/include/nlohmann/detail/conversions/to_json.hpp
index c3ac5aa8f..fc3548a12 100644
--- a/include/nlohmann/detail/conversions/to_json.hpp
+++ b/include/nlohmann/detail/conversions/to_json.hpp
@@ -1,7 +1,6 @@
 #pragma once
 
 #include <algorithm> // copy
-#include <ciso646> // or, and, not
 #include <iterator> // begin, end
 #include <string> // string
 #include <tuple> // tuple, get
diff --git a/include/nlohmann/detail/iterators/iter_impl.hpp b/include/nlohmann/detail/iterators/iter_impl.hpp
index 336aba1a4..9878f5ee5 100644
--- a/include/nlohmann/detail/iterators/iter_impl.hpp
+++ b/include/nlohmann/detail/iterators/iter_impl.hpp
@@ -1,6 +1,5 @@
 #pragma once
 
-#include <ciso646> // not
 #include <iterator> // iterator, random_access_iterator_tag, bidirectional_iterator_tag, advance, next
 #include <type_traits> // conditional, is_const, remove_const
 
diff --git a/include/nlohmann/detail/meta/cpp_future.hpp b/include/nlohmann/detail/meta/cpp_future.hpp
index 948cd4fb0..dd929ee14 100644
--- a/include/nlohmann/detail/meta/cpp_future.hpp
+++ b/include/nlohmann/detail/meta/cpp_future.hpp
@@ -1,6 +1,5 @@
 #pragma once
 
-#include <ciso646> // not
 #include <cstddef> // size_t
 #include <type_traits> // conditional, enable_if, false_type, integral_constant, is_constructible, is_integral, is_same, remove_cv, remove_reference, true_type
 
diff --git a/include/nlohmann/detail/meta/type_traits.hpp b/include/nlohmann/detail/meta/type_traits.hpp
index 2b2b2d3ba..fdabd2af6 100644
--- a/include/nlohmann/detail/meta/type_traits.hpp
+++ b/include/nlohmann/detail/meta/type_traits.hpp
@@ -1,6 +1,5 @@
 #pragma once
 
-#include <ciso646> // not
 #include <limits> // numeric_limits
 #include <type_traits> // false_type, is_constructible, is_integral, is_same, true_type
 #include <utility> // declval
diff --git a/include/nlohmann/detail/output/serializer.hpp b/include/nlohmann/detail/output/serializer.hpp
index 0a4ddbdaa..f38376e81 100644
--- a/include/nlohmann/detail/output/serializer.hpp
+++ b/include/nlohmann/detail/output/serializer.hpp
@@ -3,7 +3,6 @@
 #include <algorithm> // reverse, remove, fill, find, none_of
 #include <array> // array
 #include <cassert> // assert
-#include <ciso646> // and, or
 #include <clocale> // localeconv, lconv
 #include <cmath> // labs, isfinite, isnan, signbit
 #include <cstddef> // size_t, ptrdiff_t
diff --git a/include/nlohmann/detail/value_t.hpp b/include/nlohmann/detail/value_t.hpp
index c4552df91..0a160e91d 100644
--- a/include/nlohmann/detail/value_t.hpp
+++ b/include/nlohmann/detail/value_t.hpp
@@ -1,7 +1,6 @@
 #pragma once
 
 #include <array> // array
-#include <ciso646> // and
 #include <cstddef> // size_t
 #include <cstdint> // uint8_t
 #include <string> // string
diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index 895a8ec1d..88f775447 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -36,7 +36,6 @@ SOFTWARE.
 
 #include <algorithm> // all_of, find, for_each
 #include <cassert> // assert
-#include <ciso646> // and, not, or
 #include <cstddef> // nullptr_t, ptrdiff_t, size_t
 #include <functional> // hash, less
 #include <initializer_list> // initializer_list
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index c51f4f8bf..3bbe136ac 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -36,7 +36,6 @@ SOFTWARE.
 
 #include <algorithm> // all_of, find, for_each
 #include <cassert> // assert
-#include <ciso646> // and, not, or
 #include <cstddef> // nullptr_t, ptrdiff_t, size_t
 #include <functional> // hash, less
 #include <initializer_list> // initializer_list
@@ -58,7 +57,6 @@ SOFTWARE.
 
 #include <algorithm> // transform
 #include <array> // array
-#include <ciso646> // and, not
 #include <forward_list> // forward_list
 #include <iterator> // inserter, front_inserter, end
 #include <map> // map
@@ -2088,7 +2086,6 @@ class other_error : public exception
 // #include <nlohmann/detail/meta/cpp_future.hpp>
 
 
-#include <ciso646> // not
 #include <cstddef> // size_t
 #include <type_traits> // conditional, enable_if, false_type, integral_constant, is_constructible, is_integral, is_same, remove_cv, remove_reference, true_type
 
@@ -2153,7 +2150,6 @@ constexpr T static_const<T>::value;
 // #include <nlohmann/detail/meta/type_traits.hpp>
 
 
-#include <ciso646> // not
 #include <limits> // numeric_limits
 #include <type_traits> // false_type, is_constructible, is_integral, is_same, true_type
 #include <utility> // declval
@@ -2711,7 +2707,6 @@ struct is_compatible_type
 
 
 #include <array> // array
-#include <ciso646> // and
 #include <cstddef> // size_t
 #include <cstdint> // uint8_t
 #include <string> // string
@@ -3160,7 +3155,6 @@ constexpr const auto& from_json = detail::static_const<detail::from_json_fn>::va
 
 
 #include <algorithm> // copy
-#include <ciso646> // or, and, not
 #include <iterator> // begin, end
 #include <string> // string
 #include <tuple> // tuple, get
@@ -9196,7 +9190,6 @@ template<typename BasicJsonType> struct internal_iterator
 // #include <nlohmann/detail/iterators/iter_impl.hpp>
 
 
-#include <ciso646> // not
 #include <iterator> // iterator, random_access_iterator_tag, bidirectional_iterator_tag, advance, next
 #include <type_traits> // conditional, is_const, remove_const
 
@@ -12531,7 +12524,6 @@ class binary_writer
 #include <algorithm> // reverse, remove, fill, find, none_of
 #include <array> // array
 #include <cassert> // assert
-#include <ciso646> // and, or
 #include <clocale> // localeconv, lconv
 #include <cmath> // labs, isfinite, isnan, signbit
 #include <cstddef> // size_t, ptrdiff_t
@@ -12547,7 +12539,6 @@ class binary_writer
 
 #include <array> // array
 #include <cassert> // assert
-#include <ciso646> // or, and, not
 #include <cmath>   // signbit, isfinite
 #include <cstdint> // intN_t, uintN_t
 #include <cstring> // memcpy, memmove