diff --git a/cstool/cstool.c b/cstool/cstool.c
index 6d7f1996..79144286 100644
--- a/cstool/cstool.c
+++ b/cstool/cstool.c
@@ -1,6 +1,4 @@
 /* Tang Yuhang <tyh000011112222@gmail.com> 2016 */
-#include <stdio.h>
-#include <inttypes.h>
 #include <string.h>
 #include <ctype.h>
 #include <errno.h>
diff --git a/include/platform.h b/include/platform.h
index 2ff28d3e..8c1ce7b4 100644
--- a/include/platform.h
+++ b/include/platform.h
@@ -90,6 +90,11 @@ typedef unsigned long long uint64_t;
 #define PRIX32        "X"
 #endif
 
+#if defined(_MSC_VER) && _MSC_VER <= 1700
+// redefine functions from inttypes.h used in cstool
+#define strtoull _strtoui64
+#endif
+
 #define PRId64        __PRI_64_LENGTH_MODIFIER__ "d"
 #define PRIi64        __PRI_64_LENGTH_MODIFIER__ "i"
 #define PRIo64        __PRI_64_LENGTH_MODIFIER__ "o"