diff --git a/packages/config/src/load.js b/packages/config/src/load.js
index 95f3f436d9..d531ac2f92 100644
--- a/packages/config/src/load.js
+++ b/packages/config/src/load.js
@@ -177,7 +177,7 @@ function expand (target, source = {}, parse = v => v) {
         value = interpolate(value)
       }
 
-      return newValue.replace(replacePart, value)
+      return value !== undefined ? newValue.replace(replacePart, value) : newValue
     }, value))
   }
 
diff --git a/test/fixtures/runtime-config/.env b/test/fixtures/runtime-config/.env
index 138fca756f..3bff1d2f7d 100644
--- a/test/fixtures/runtime-config/.env
+++ b/test/fixtures/runtime-config/.env
@@ -2,3 +2,4 @@ BASE_URL=/api
 PUBLIC_URL=https://google.com
 SERVER_BASE_URL
 API_SECRET=1234
+TOKEN=$2yr$10$tN3JmuvXZKGwi0l38A.SxUVemGrFJiyLunyqkOqOTE7LHsrSwMEmEB
diff --git a/test/fixtures/runtime-config/nuxt.config.js b/test/fixtures/runtime-config/nuxt.config.js
index a6f7f7c9c1..7bee052b0b 100644
--- a/test/fixtures/runtime-config/nuxt.config.js
+++ b/test/fixtures/runtime-config/nuxt.config.js
@@ -1,7 +1,8 @@
 export default {
   publicRuntimeConfig: {
     baseURL: process.env.BASE_URL,
-    isFixture: true
+    isFixture: true,
+    TOKEN: 'default'
   },
   privateRuntimeConfig: {
     baseURL: '${PUBLIC_URL}${BASE_URL}',