diff --git a/src/util.h b/src/util.h
index 4b0814c6..eb8f781c 100644
--- a/src/util.h
+++ b/src/util.h
@@ -54,6 +54,17 @@ static const int64 CENT = 1000000;
 #endif
 #endif
 
+/* Format characters for (s)size_t and ptrdiff_t */
+#if defined(_MSC_VER) || defined(__MSVCRT__)
+  #define PRIszx    "%Ix"
+  #define PRIszu    "%Iu"
+  #define PRIszd    "%Id"
+#else
+  #define PRIszx    "%zx"
+  #define PRIszu    "%zu"
+  #define PRIszd    "%zd"
+#endif
+
 // This is needed because the foreach macro can't get over the comma in pair<t1, t2>
 #define PAIRTYPE(t1, t2)    std::pair<t1, t2>