diff --git a/lib/nodejs/lib/thrift/int64_util.js b/lib/nodejs/lib/thrift/int64_util.js
index ecba439..e8d707d 100644
--- a/lib/nodejs/lib/thrift/int64_util.js
+++ b/lib/nodejs/lib/thrift/int64_util.js
@@ -40,7 +40,7 @@
       var incremented = false;
       var buffer = new Buffer(8);
       for (var i = 7; i >= 0; --i) {
-        buffer[i] = ~b[o + i] + (incremented ? 0 : 1);
+        buffer[i] = (~b[o + i] + (incremented ? 0 : 1)) & 0xff;
         incremented |= b[o + i];
       }
       b = buffer;