diff --git a/middleware/lru-cache.js b/middleware/lru-cache.js
index 073408f06..5c8790ffb 100644
--- a/middleware/lru-cache.js
+++ b/middleware/lru-cache.js
@@ -26,7 +26,7 @@ module.exports = function(options = {}) {
             }
         },
         set: (key, value, maxAge) => {
-            if (!value) {
+            if (!value || value === 'undefined') {
                 value = '';
             }
             if (typeof value === 'object') {
diff --git a/middleware/redis-cache.js b/middleware/redis-cache.js
index 309ae776c..0cc8d4f72 100644
--- a/middleware/redis-cache.js
+++ b/middleware/redis-cache.js
@@ -47,7 +47,7 @@ module.exports = function(options = {}) {
             }
         },
         set: async (key, value, maxAge) => {
-            if (!value) {
+            if (!value || value === 'undefined') {
                 value = '';
             }
             if (typeof value === 'object') {