diff --git a/spine-ts/spine-phaser/src/require-shim.ts b/spine-ts/spine-phaser/src/require-shim.ts
index 49f6287d7..6281cfd84 100644
--- a/spine-ts/spine-phaser/src/require-shim.ts
+++ b/spine-ts/spine-phaser/src/require-shim.ts
@@ -30,7 +30,7 @@
 declare global {
 	var require: any;
 }
-if (window.Phaser) {
+if (typeof window !== 'undefined' && window.Phaser) {
 	let prevRequire = window.require;
 	window.require = (x: string) => {
 		if (prevRequire) return prevRequire(x);
diff --git a/spine-ts/spine-pixi/src/require-shim.ts b/spine-ts/spine-pixi/src/require-shim.ts
index 051f22e23..498ea8bd3 100644
--- a/spine-ts/spine-pixi/src/require-shim.ts
+++ b/spine-ts/spine-pixi/src/require-shim.ts
@@ -32,7 +32,7 @@ declare global {
 	var PIXI: any;
 }
 
-if (window.PIXI) {
+if (typeof window !== 'undefined' && window.PIXI) {
 	let prevRequire = window.require;
 	window.require = (x: string) => {
 		if (prevRequire) return prevRequire(x);
diff --git a/spine-ts/spine-threejs/src/require-shim.ts b/spine-ts/spine-threejs/src/require-shim.ts
index e315fe12e..a75fbbe4c 100644
--- a/spine-ts/spine-threejs/src/require-shim.ts
+++ b/spine-ts/spine-threejs/src/require-shim.ts
@@ -31,7 +31,7 @@ declare global {
 	var require: any;
 }
 
-if (window.THREE) {
+if (typeof window !== 'undefined' && window.THREE) {
 	let prevRequire = window.require;
 	window.require = (x: string) => {
 		if (prevRequire) return prevRequire(x);