diff --git a/setup/setup.js b/setup/setup.js
index ad774bc11..eeb17422c 100644
--- a/setup/setup.js
+++ b/setup/setup.js
@@ -47,7 +47,7 @@ function checkSymlinkExistsAsync() {
 }
 
 function ensureYarnInstalledAsync() {
-	var semverPattern = /^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(-(0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(\.(0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*)?(\+[0-9a-zA-Z-]+(\.[0-9a-zA-Z-]+)*)?$/;
+	const semverPattern = /^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(-(0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(\.(0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*)?(\+[0-9a-zA-Z-]+(\.[0-9a-zA-Z-]+)*)?$/;
 	return execGetOutput("yarn", ["-v"], "Check yarn version")
 		.then(stdout => semverPattern.test(stdout), () => false)
 		.then(hasYarn => hasYarn || installYarnAsync());