https://bugs.gentoo.org/895130
--- a/external/pybind11/include/pybind11/attr.h
+++ b/external/pybind11/include/pybind11/attr.h
@@ -10,6 +10,7 @@
 
 #pragma once
 
+#include <cstdint>
 #include "cast.h"
 
 PYBIND11_NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
--- a/include/tweedledum/IR/Cbit.h
+++ b/include/tweedledum/IR/Cbit.h
@@ -5,6 +5,7 @@
 #pragma once
 
 #include <cassert>
+#include <cstdint>
 #include <limits>
 #include <string>
 #include <vector>
