diff --git a/cpp/src/Slice/MD5I.cpp b/cpp/src/Slice/MD5I.cpp
index 66f4de545b..271352d1ea 100644
--- a/cpp/src/Slice/MD5I.cpp
+++ b/cpp/src/Slice/MD5I.cpp
@@ -52,6 +52,7 @@
  */

 #include <Slice/MD5I.h>
+#include <stdint.h>
 #include <string.h>

 #ifdef __GNUC__
@@ -172,7 +173,7 @@ md5_process(md5_state_t *pms, const md5_byte_t *data /*[64]*/)
              * On little-endian machines, we can process properly aligned
              * data without copying it.
              */
-            if (!((data - (const md5_byte_t *)0) & 3)) {
+            if (!((reinterpret_cast<uintptr_t>(data)) & 3)) {
                 /* data are properly aligned */
                 X = (const md5_word_t *)data;
             } else {