diff --git a/src/SASjs.ts b/src/SASjs.ts
index 9167280..583e78c 100644
--- a/src/SASjs.ts
+++ b/src/SASjs.ts
@@ -2,7 +2,9 @@ import { isIEorEdgeOrOldFirefox } from "./utils/isIeOrEdge";
 import * as e6p from "es6-promise";
 (e6p as any).polyfill();
 if (isIEorEdgeOrOldFirefox()) {
-  window.fetch = undefined as any; // ensure the polyfill runs
+  if (window) {
+    window.fetch = undefined as any; // ensure the polyfill runs
+  }
 }
 // tslint:disable-next-line
 require("isomorphic-fetch");
diff --git a/src/utils/isIeOrEdge.ts b/src/utils/isIeOrEdge.ts
index 59400da..2a57ac3 100644
--- a/src/utils/isIeOrEdge.ts
+++ b/src/utils/isIeOrEdge.ts
@@ -1,4 +1,7 @@
 export function isIEorEdgeOrOldFirefox() {
+  if (typeof window === "undefined") {
+    return false;
+  }
   const ua = window.navigator.userAgent;
 
   if (ua.indexOf("Firefox") > 0) {