diff --git a/packages/time/get-running-time.js b/packages/time/get-running-time.js
index 685f1763..4271f0d8 100644
--- a/packages/time/get-running-time.js
+++ b/packages/time/get-running-time.js
@@ -43,10 +43,15 @@ async function getThrottling () {
 }
 
 let throttlingCache
+let throttlingCalculating
 
 module.exports = async function getRunningTime (file) {
   if (!JS_FILES.test(file)) return 0
-  if (!throttlingCache) throttlingCache = await getThrottling()
+  if (throttlingCalculating) await throttlingCalculating
+  if (!throttlingCache) {
+    throttlingCalculating = getThrottling()
+    throttlingCache = await throttlingCalculating
+  }
   return getTime(file, throttlingCache)
 }
 
diff --git a/packages/time/test/get-running-time.test.js b/packages/time/test/get-running-time.test.js
index 56ff851f..d6b38e6e 100644
--- a/packages/time/test/get-running-time.test.js
+++ b/packages/time/test/get-running-time.test.js
@@ -34,3 +34,13 @@ it('uses cache', async () => {
 it('ignores non-JS files', async () => {
   expect(await getRunningTime('/a.jpg')).toEqual(0)
 })
+
+it('works in parallel', async () => {
+  let times = await Promise.all([
+    getRunningTime(EXAMPLE),
+    getRunningTime(EXAMPLE),
+    getRunningTime(EXAMPLE),
+    getRunningTime(EXAMPLE)
+  ])
+  expect(times).toHaveLength(5)
+})