diff --git a/ciphers/uint128_t.hpp b/ciphers/uint128_t.hpp
index d50cb4ffb..141864c8d 100644
--- a/ciphers/uint128_t.hpp
+++ b/ciphers/uint128_t.hpp
@@ -8,6 +8,7 @@
  */
 
 #include <algorithm>  /// for `std::reverse` and other operations
+#include <cstdint>    /// for integral typedefs
 #include <ostream>    /// for `std::cout` overload
 #include <string>     /// for `std::string`
 #include <utility>    /// for `std::pair` library