diff --git a/src/vim.h b/src/vim.h
index c84d5a5..9e4c61d 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -340,9 +340,9 @@
 #ifdef _WIN64
 typedef unsigned __int64	long_u;
 typedef		 __int64	long_i;
-# define SCANF_HEX_LONG_U       "%Ix"
-# define SCANF_DECIMAL_LONG_U   "%Iu"
-# define PRINTF_HEX_LONG_U      "0x%Ix"
+# define SCANF_HEX_LONG_U       "%llx"
+# define SCANF_DECIMAL_LONG_U   "%llu"
+# define PRINTF_HEX_LONG_U      "0x%llx"
 #else
   // Microsoft-specific. The __w64 keyword should be specified on any typedefs
   // that change size between 32-bit and 64-bit platforms.  For any such type,