diff --git a/include/chibi/sexp.h b/include/chibi/sexp.h
index 90cbbb53..c5fa449e 100755
--- a/include/chibi/sexp.h
+++ b/include/chibi/sexp.h
@@ -256,7 +256,7 @@ typedef short sexp_int32_t;
 # endif
 #endif
 
-#ifdef __APPLE__
+#if defined(__APPLE__) || defined(_WIN64)
 #define PRIoff "%lld"
 #else
 #define PRIoff "%ld"