diff --git a/server/utils/createMutex.js b/server/utils/createMutex.js
deleted file mode 100644
index 7094c8b..0000000
--- a/server/utils/createMutex.js
+++ /dev/null
@@ -1,34 +0,0 @@
-const invariant = require("invariant");
-
-function defaultCreateKey(payload) {
-  return payload;
-}
-
-function createMutex(doWork, createKey = defaultCreateKey) {
-  const mutex = Object.create(null);
-
-  return (payload, callback) => {
-    const key = createKey(payload);
-
-    invariant(
-      typeof key === "string",
-      "Mutex needs a string key; please provide a createKey function that returns a string"
-    );
-
-    if (mutex[key]) {
-      mutex[key].push(callback);
-    } else {
-      mutex[key] = [callback];
-
-      doWork(payload, (error, value) => {
-        mutex[key].forEach(callback => {
-          callback(error, value);
-        });
-
-        delete mutex[key];
-      });
-    }
-  };
-}
-
-module.exports = createMutex;
diff --git a/server/utils/getNpmPackageInfo.js b/server/utils/getNpmPackageInfo.js
index 6bb6b47..6827e49 100644
--- a/server/utils/getNpmPackageInfo.js
+++ b/server/utils/getNpmPackageInfo.js
@@ -1,54 +1,37 @@
 const cache = require("./cache");
-const createMutex = require("./createMutex");
 const fetchNpmPackageInfo = require("./fetchNpmPackageInfo");
 
 const notFound = "PackageNotFound";
 
-const mutex = createMutex((packageName, callback) => {
-  const key = `packageInfo2-${packageName}`;
+function getNpmPackageInfo(packageName) {
+  return new Promise((resolve, reject) => {
+    const key = `npmPackageInfo-${packageName}`;
 
-  cache.get(key, (error, value) => {
-    if (error) {
-      callback(error);
-    } else if (value != null) {
-      callback(null, value === notFound ? null : JSON.parse(value));
-    } else {
-      fetchNpmPackageInfo(packageName).then(
-        value => {
+    cache.get(key, (error, value) => {
+      if (error) {
+        reject(error);
+      } else if (value != null) {
+        resolve(value === notFound ? null : JSON.parse(value));
+      } else {
+        fetchNpmPackageInfo(packageName).then(value => {
           if (value == null) {
+            resolve(null);
+
             // Cache 404s for 5 minutes. This prevents us from making
             // unnecessary requests to the registry for bad package names.
             // In the worst case, a brand new package's info will be
             // available within 5 minutes.
-            cache.setex(key, 300, notFound, () => {
-              callback(null, null);
-            });
+            cache.setex(key, 300, notFound);
           } else {
+            resolve(value);
+
             // Cache valid package info for 1 minute. In the worst case,
             // new versions won't be available for 1 minute.
             cache.setnx(key, JSON.stringify(value), (error, reply) => {
               if (reply === 1) cache.expire(key, 60);
-              callback(null, value);
             });
           }
-        },
-        error => {
-          // Do not cache errors.
-          cache.del(key);
-          callback(error);
-        }
-      );
-    }
-  });
-});
-
-function getNpmPackageInfo(packageName) {
-  return new Promise((resolve, reject) => {
-    mutex(packageName, (error, value) => {
-      if (error) {
-        reject(error);
-      } else {
-        resolve(value);
+        }, reject);
       }
     });
   });