diff --git a/install/package.json b/install/package.json
index 8de0bf1e98..45bc366458 100644
--- a/install/package.json
+++ b/install/package.json
@@ -70,7 +70,7 @@
         "less": "^2.7.3",
         "lodash": "^4.17.10",
         "logrotate-stream": "^0.2.5",
-        "lru-cache": "4.1.5",
+        "lru-cache": "5.1.1",
         "material-design-lite": "^1.3.0",
         "mime": "^2.2.0",
         "mkdirp": "^0.5.1",
diff --git a/src/analytics.js b/src/analytics.js
index ef7656f674..b9649f85cc 100644
--- a/src/analytics.js
+++ b/src/analytics.js
@@ -26,7 +26,7 @@ var uniquevisitors = 0;
  * the cache could be exhausted continuously if there are more than 500 concurrently
  * active users
  */
-var ipCache = LRU({
+var ipCache = new LRU({
 	max: 500,
 	length: function () { return 1; },
 	maxAge: 0,
diff --git a/src/cache.js b/src/cache.js
index 6e54b7e0f1..02a0ffed2e 100644
--- a/src/cache.js
+++ b/src/cache.js
@@ -3,7 +3,7 @@
 var LRU = require('lru-cache');
 var pubsub = require('./pubsub');
 
-var cache = LRU({
+var cache = new LRU({
 	max: 1000,
 	maxAge: 0,
 });
diff --git a/src/database/cache.js b/src/database/cache.js
index b8f48e5b73..5bb6cb8c33 100644
--- a/src/database/cache.js
+++ b/src/database/cache.js
@@ -4,7 +4,7 @@ module.exports.create = function (name) {
 	var LRU = require('lru-cache');
 	var pubsub = require('../pubsub');
 
-	var cache = LRU({
+	var cache = new LRU({
 		max: 20000,
 		length: function () { return 1; },
 		maxAge: 0,
diff --git a/src/groups/cache.js b/src/groups/cache.js
index 627327ff94..70e4f85472 100644
--- a/src/groups/cache.js
+++ b/src/groups/cache.js
@@ -3,7 +3,7 @@
 var LRU = require('lru-cache');
 var pubsub = require('../pubsub');
 
-var cache = LRU({
+var cache = new LRU({
 	max: 40000,
 	maxAge: 0,
 });
diff --git a/src/middleware/index.js b/src/middleware/index.js
index 3328cee7b5..91d5a0e01d 100644
--- a/src/middleware/index.js
+++ b/src/middleware/index.js
@@ -22,7 +22,7 @@ var controllers = {
 	helpers: require('../controllers/helpers'),
 };
 
-var delayCache = LRU({
+var delayCache = new LRU({
 	maxAge: 1000 * 60,
 });
 
diff --git a/src/posts/cache.js b/src/posts/cache.js
index 7d45ba8631..4d03cd3db1 100644
--- a/src/posts/cache.js
+++ b/src/posts/cache.js
@@ -3,7 +3,7 @@
 var LRU = require('lru-cache');
 var meta = require('../meta');
 
-var cache = LRU({
+var cache = new LRU({
 	max: meta.config.postCacheSize,
 	length: function (n) { return n.length; },
 	maxAge: 0,
diff --git a/src/user/blocks.js b/src/user/blocks.js
index 3dfa429935..934a3cba87 100644
--- a/src/user/blocks.js
+++ b/src/user/blocks.js
@@ -9,7 +9,7 @@ var pubsub = require('../pubsub');
 
 module.exports = function (User) {
 	User.blocks = {
-		_cache: LRU({
+		_cache: new LRU({
 			max: 100,
 			length: function () { return 1; },
 			maxAge: 0,