diff --git a/nbt.js b/nbt.js
index 080fff8..12636e4 100644
--- a/nbt.js
+++ b/nbt.js
@@ -66,7 +66,7 @@
 			/* FIXME: this can overflow, JS has 53 bit precision */
 			var upper = this.int();
 			var lower = this.int();
-			return (upper << 32) + lower;
+			return (upper * 4294967296) + lower;
 		};
 
 		this[nbt.tagTypes.byteArray] = function() {