diff --git a/lib/config.ts b/lib/config.ts
index 7e44038..839a62e 100644
--- a/lib/config.ts
+++ b/lib/config.ts
@@ -113,21 +113,22 @@ export const isSearchEnabled: boolean = getSiteConfig('isSearchEnabled', true)
 // ----------------------------------------------------------------------------
 
 // Optional redis instance for persisting preview images
-export const isRedisEnabled: boolean = getSiteConfig('isRedisEnabled', false)
+export const isRedisEnabled: boolean =
+  getSiteConfig('isRedisEnabled', false) || !!getEnv('REDIS_ENABLED')
 
 // (if you want to enable redis, only REDIS_HOST and REDIS_PASSWORD are required)
 // we recommend that you store these in a local `.env` file
-export const redisHost: string | undefined = getEnv('REDIS_HOST')
-export const redisPassword: string | undefined = getEnv('REDIS_PASSWORD')
-export const redisUser: string | undefined = getEnv('REDIS_USER', 'default')
+export const redisHost = getEnv('REDIS_HOST', isRedisEnabled ? undefined : null)
+export const redisPassword = getEnv(
+  'REDIS_PASSWORD',
+  isRedisEnabled ? undefined : null
+)
+export const redisUser: string = getEnv('REDIS_USER', 'default')
 export const redisUrl = getEnv(
   'REDIS_URL',
-  `redis://${redisUser}:${redisPassword}@${redisHost}`
-)
-export const redisNamespace: string | undefined = getEnv(
-  'REDIS_NAMESPACE',
-  'preview-images'
+  isRedisEnabled ? `redis://${redisUser}:${redisPassword}@${redisHost}` : null
 )
+export const redisNamespace = getEnv('REDIS_NAMESPACE', 'preview-images')
 
 // ----------------------------------------------------------------------------
 
diff --git a/lib/get-config-value.ts b/lib/get-config-value.ts
index 4ba17f8..2faf917 100644
--- a/lib/get-config-value.ts
+++ b/lib/get-config-value.ts
@@ -49,15 +49,15 @@ export function getRequiredSiteConfig<T>(key: string): T {
 
 export const isServer = typeof window === 'undefined'
 
-export function getEnv(
+export function getEnv<T>(
   key: string,
-  defaultValue?: string,
+  defaultValue?: string | T,
   env = process.env
-): string | undefined {
+): string | T {
   const value = env[key]
 
   if (value !== undefined) {
-    return value
+    return value as string
   }
 
   if (defaultValue !== undefined) {
@@ -67,4 +67,6 @@ export function getEnv(
   if (isServer) {
     throw new Error(`Config error: missing required env variable "${key}"`)
   }
+
+  return null as unknown as T
 }