--- a/include/picojson/picojson.h	(index)
+++ b/include/picojson/picojson.h	(working tree)
@@ -487,1 +487,5 @@ inline std::string value::to_str() const {
-    SNPRINTF(buf, sizeof(buf), "%" PRId64, u_.int64_);
+#if defined(__APPLE__)
+    SNPRINTF(buf, sizeof(buf), "%lld", u_.int64_);
+#else
+    SNPRINTF(buf, sizeof(buf), "%" PRId64, u_.int64_);
+#endif