diff --git a/include/continuable/continuable-base.hpp b/include/continuable/continuable-base.hpp
index 02368e3..f8a0229 100644
--- a/include/continuable/continuable-base.hpp
+++ b/include/continuable/continuable-base.hpp
@@ -32,7 +32,7 @@
 #define CONTINUABLE_BASE_HPP_INCLUDED
 
 #include <cassert>
-#include <cstdint>
+#include <cstddef>
 #include <type_traits>
 #include <utility>
 
diff --git a/include/continuable/continuable-trait.hpp b/include/continuable/continuable-trait.hpp
index ec88c5d..1777535 100644
--- a/include/continuable/continuable-trait.hpp
+++ b/include/continuable/continuable-trait.hpp
@@ -31,7 +31,7 @@
 #ifndef CONTINUABLE_TRAIT_HPP_INCLUDED
 #define CONTINUABLE_TRAIT_HPP_INCLUDED
 
-#include <cstdint>
+#include <cstddef>
 
 #include <continuable/continuable-base.hpp>
 #include <continuable/continuable-promise-base.hpp>
diff --git a/include/continuable/continuable-types.hpp b/include/continuable/continuable-types.hpp
index 2536749..1686d89 100644
--- a/include/continuable/continuable-types.hpp
+++ b/include/continuable/continuable-types.hpp
@@ -31,7 +31,7 @@
 #ifndef CONTINUABLE_TYPES_HPP_INCLUDED
 #define CONTINUABLE_TYPES_HPP_INCLUDED
 
-#include <cstdint>
+#include <cstddef>
 
 #include <function2/function2.hpp>
 
diff --git a/include/continuable/detail/flat-variant.hpp b/include/continuable/detail/flat-variant.hpp
index ecc43e0..ba4a1f1 100644
--- a/include/continuable/detail/flat-variant.hpp
+++ b/include/continuable/detail/flat-variant.hpp
@@ -32,6 +32,7 @@
 #define CONTINUABLE_DETAIL_FLAT_VARIANT_HPP_INCLUDED
 
 #include <cassert>
+#include <cstddef>
 #include <cstdint>
 #include <limits>
 #include <memory>
diff --git a/include/continuable/detail/traits.hpp b/include/continuable/detail/traits.hpp
index e5a8d68..9b40d2f 100644
--- a/include/continuable/detail/traits.hpp
+++ b/include/continuable/detail/traits.hpp
@@ -31,7 +31,7 @@
 #ifndef CONTINUABLE_DETAIL_TRAITS_HPP_INCLUDED
 #define CONTINUABLE_DETAIL_TRAITS_HPP_INCLUDED
 
-#include <cstdint>
+#include <cstddef>
 #include <tuple>
 #include <type_traits>
 #include <utility>