--- a/libcaf_core/caf/detail/ripemd_160.hpp
+++ b/libcaf_core/caf/detail/ripemd_160.hpp
@@ -41,6 +41,7 @@
 #pragma once

 #include <array>
+#include <cstdint>
 #include <string>

 #include "caf/detail/core_export.hpp"