diff --git a/src/combineReducers.js b/src/combineReducers.js
index b5de20aecf..b40927e1be 100644
--- a/src/combineReducers.js
+++ b/src/combineReducers.js
@@ -121,7 +121,7 @@ export default function combineReducers(reducers) {
   for (let i = 0; i < reducerKeys.length; i++) {
     const key = reducerKeys[i]
 
-    if (process.env.NODE_ENV !== 'production') {
+    if (typeof process === 'object' && process.env.NODE_ENV !== 'production') {
       if (typeof reducers[key] === 'undefined') {
         warning(`No reducer provided for key "${key}"`)
       }
@@ -134,7 +134,7 @@ export default function combineReducers(reducers) {
   const finalReducerKeys = Object.keys(finalReducers)
 
   let unexpectedKeyCache
-  if (process.env.NODE_ENV !== 'production') {
+  if (typeof process === 'object' && process.env.NODE_ENV !== 'production') {
     unexpectedKeyCache = {}
   }
 
@@ -150,7 +150,7 @@ export default function combineReducers(reducers) {
       throw shapeAssertionError
     }
 
-    if (process.env.NODE_ENV !== 'production') {
+    if (typeof process === 'object' && process.env.NODE_ENV !== 'production') {
       const warningMessage = getUnexpectedStateShapeWarningMessage(
         state,
         finalReducers,
diff --git a/src/index.js b/src/index.js
index bac914de17..29a41efdae 100644
--- a/src/index.js
+++ b/src/index.js
@@ -13,6 +13,7 @@ import __DO_NOT_USE__ActionTypes from './utils/actionTypes'
 function isCrushed() {}
 
 if (
+  typeof process === 'object' &&
   process.env.NODE_ENV !== 'production' &&
   typeof isCrushed.name === 'string' &&
   isCrushed.name !== 'isCrushed'