diff --git a/src/pycryptopp/cipher/aesmodule.cpp b/src/pycryptopp/cipher/aesmodule.cpp
index 360827d..3d0b95a 100644
--- a/src/pycryptopp/cipher/aesmodule.cpp
+++ b/src/pycryptopp/cipher/aesmodule.cpp
@@ -20,6 +20,9 @@ typedef int Py_ssize_t;
 #include <src-cryptopp/aes.h>
 #endif
 
+// https://github.com/weidai11/cryptopp/issues/442
+typedef unsigned char byte;
+
 static const char*const aes___doc__ = "_aes counter mode cipher\n\
 You are advised to run aes.start_up_self_test() after importing this module.";
 
diff --git a/src/pycryptopp/cipher/xsalsa20module.cpp b/src/pycryptopp/cipher/xsalsa20module.cpp
index ab29787..a0b7c71 100644
--- a/src/pycryptopp/cipher/xsalsa20module.cpp
+++ b/src/pycryptopp/cipher/xsalsa20module.cpp
@@ -16,6 +16,9 @@ typedef int Py_ssize_t;
 #include <src-cryptopp/salsa.h>
 #endif
 
+// https://github.com/weidai11/cryptopp/issues/442
+typedef unsigned char byte;
+
 static const char* const xsalsa20__doc__ = "_xsalsa20 cipher";
 
 static PyObject *xsalsa20_error;
diff --git a/src/pycryptopp/hash/sha256module.cpp b/src/pycryptopp/hash/sha256module.cpp
index bf9d8e3..8272e6c 100644
--- a/src/pycryptopp/hash/sha256module.cpp
+++ b/src/pycryptopp/hash/sha256module.cpp
@@ -21,6 +21,9 @@ typedef int Py_ssize_t;
 #include <src-cryptopp/filters.h>
 #endif
 
+// https://github.com/weidai11/cryptopp/issues/442
+typedef unsigned char byte;
+
 static const char*const sha256___doc__ = "_sha256 hash function";
 
 static PyObject *sha256_error;