include: Fix the definition of 64-bit types for Mingw64.
diff --git a/include/basetsd.h b/include/basetsd.h
index 8f853a4..409f958 100644
--- a/include/basetsd.h
+++ b/include/basetsd.h
@@ -59,7 +59,7 @@
 #    define __int32 int
 #  endif
 #  ifndef __int64
-#    ifdef _WIN64
+#    if defined(_WIN64) && !defined(__MINGW64__)
 #      define __int64 long
 #    else
 #      define __int64 long long