diff -wur oniguruma.orig/src/config.h.win32 oniguruma/src/config.h.win32
--- oniguruma.orig/src/config.h.win32	2017-07-13 17:12:45.228068900 +0200
+++ oniguruma/src/config.h.win32	2017-07-13 16:11:19.955226200 +0200
@@ -15,6 +15,7 @@
 #define SIZEOF_VOIDP 4
 #define SIZEOF_FLOAT 4
 #define SIZEOF_DOUBLE 8
+#define SIZEOF_SIZE_T 4
 #define HAVE_PROTOTYPES 1
 #define TOKEN_PASTE(x,y) x##y
 #define HAVE_STDARG_PROTOTYPES 1
diff -wur oniguruma.orig/src/config.h.win64 oniguruma/src/config.h.win64
--- oniguruma.orig/src/config.h.win64	2017-07-13 17:12:45.273605000 +0200
+++ oniguruma/src/config.h.win64	2017-07-13 16:11:19.957231300 +0200
@@ -15,6 +15,7 @@
 #define SIZEOF_VOIDP 8
 #define SIZEOF_FLOAT 4
 #define SIZEOF_DOUBLE 8
+#define SIZEOF_SIZE_T 8
 #define HAVE_PROTOTYPES 1
 #define TOKEN_PASTE(x,y) x##y
 #define HAVE_STDARG_PROTOTYPES 1
diff -wur oniguruma.orig/src/regint.h oniguruma/src/regint.h
--- oniguruma.orig/src/regint.h	2017-07-13 17:12:48.686073300 +0200
+++ oniguruma/src/regint.h	2017-07-13 17:13:28.032286100 +0200
@@ -201,17 +201,21 @@
 } while(0)
 
 /* sizeof(OnigCodePoint) */
+#ifdef SIZEOF_SIZE_T
+# define WORD_ALIGNMENT_SIZE     SIZEOF_SIZE_T
+#else
 #define WORD_ALIGNMENT_SIZE     SIZEOF_LONG
+#endif
 
 #define GET_ALIGNMENT_PAD_SIZE(addr,pad_size) do {\
   (pad_size) = WORD_ALIGNMENT_SIZE \
-               - ((unsigned int )(addr) % WORD_ALIGNMENT_SIZE);\
+               - ((size_t)(addr) % WORD_ALIGNMENT_SIZE);\
   if ((pad_size) == WORD_ALIGNMENT_SIZE) (pad_size) = 0;\
 } while (0)
 
 #define ALIGNMENT_RIGHT(addr) do {\
   (addr) += (WORD_ALIGNMENT_SIZE - 1);\
-  (addr) -= ((unsigned int )(addr) % WORD_ALIGNMENT_SIZE);\
+  (addr) -= ((size_t)(addr) % WORD_ALIGNMENT_SIZE);\
 } while (0)
 
 #endif /* PLATFORM_UNALIGNED_WORD_ACCESS */
@@ -662,7 +666,11 @@
   BBuf*  mbuf;   /* multi-byte info or NULL */
 } CClassNode;
 
+#ifdef _WIN64
+typedef __int64 OnigStackIndex;
+#else
 typedef long OnigStackIndex;
+#endif
 
 typedef struct _OnigStackType {
   unsigned int type;
