diff --git a/matrix.js b/matrix.js
index 8ccd4c9..af456cb 100644
--- a/matrix.js
+++ b/matrix.js
@@ -140,9 +140,9 @@ class Matrix {
   print() {
     console.table(this.data);
   }
-
-
 }
 
 
-module.exports = Matrix;
+if (typeof module !== 'undefined') {
+  module.exports = Matrix;
+}