diff --git a/include/nasmint.h b/include/nasmint.h
index e353aa93..9bb935cf 100644
--- a/include/nasmint.h
+++ b/include/nasmint.h
@@ -14,7 +14,7 @@
 
 #include <limits.h>
 
-/*** 64-bit type: long or long long ***/
+/*** 64-bit type: __int64, long or long long ***/
 
 /* Some old versions of gcc <limits.h> omit LLONG_MAX */
 #ifndef LLONG_MAX
@@ -25,7 +25,25 @@
 # endif
 #endif
 
-#if LONG_MAX == 9223372036854775807L
+#ifndef _I64_MAX
+# ifdef _MSC_VER
+#  define _I64_MAX 9223372036854775807
+# else
+#  define _I64_MAX 0
+# endif
+#endif
+
+#if _I64_MAX == 9223372036854775807
+
+/* Windows-based compiler: use __int64 */
+typedef signed __int64		int64_t;
+typedef unsigned __int64	uint64_t;
+#define _scn64			"I64"
+#define _pri64			"I64"
+#define INT64_C(x)		x ## i64
+#define UINT64_C(x)		x ## ui64
+
+#elif LONG_MAX == 9223372036854775807L
 
 /* long is 64 bits */
 typedef signed long		int64_t;