diff --git a/crc32.js b/crc32.js
index ea4527b..729f8d4 100644
--- a/crc32.js
+++ b/crc32.js
@@ -1,7 +1,25 @@
 /* crc32.js (C) 2014 SheetJS -- http://sheetjs.com */
 /* vim: set ts=2: */
-var CRC32 = {};
-(function(CRC32) {
+var CRC32;
+(function (factory) {
+
+    if(typeof DO_NOT_EXPORT_CRC === 'undefined') {
+        if('object' === typeof exports) {
+            factory(exports);
+        } else if ('function' === typeof define && define.amd) {
+            define(function () {
+                var module = {};
+                factory(module);
+                return module;
+            });
+        } else {
+          factory(CRC32 = {});
+        }
+    } else {
+        factory(CRC32 = {});
+    }
+
+}(function(CRC32) {
 CRC32.version = '0.2.2';
 /* see perf/crc32table.js */
 function signed_crc_table() {
@@ -91,4 +109,4 @@ CRC32.table = table;
 CRC32.bstr = crc32_bstr;
 CRC32.buf = crc32_buf;
 CRC32.str = crc32_str;
-})(typeof exports !== "undefined" && typeof DO_NOT_EXPORT_CRC === 'undefined' ? exports : CRC32);
+}));