diff --git a/src/lib/stylesheet.js b/src/lib/stylesheet.js
index 38eec882..2781da46 100644
--- a/src/lib/stylesheet.js
+++ b/src/lib/stylesheet.js
@@ -13,7 +13,7 @@ export default class StyleSheet {
   constructor({
     name = 'stylesheet',
     optimizeForSpeed = isProd,
-    isBrowser = typeof window !== 'undefined'
+    isBrowser = typeof document !== 'undefined'
   } = {}) {
     invariant(isString(name), '`name` must be a string')
     this._name = name
diff --git a/src/stylesheet-registry.js b/src/stylesheet-registry.js
index d887265d..b3fcdf79 100644
--- a/src/stylesheet-registry.js
+++ b/src/stylesheet-registry.js
@@ -22,7 +22,7 @@ export class StyleSheetRegistry {
   constructor({
     styleSheet = null,
     optimizeForSpeed = false,
-    isBrowser = typeof window !== 'undefined'
+    isBrowser = typeof document !== 'undefined'
   } = {}) {
     this._sheet =
       styleSheet ||