diff --git a/app/Models/Invoice.php b/app/Models/Invoice.php
index 239745a27531..b4dbbbf8fa05 100644
--- a/app/Models/Invoice.php
+++ b/app/Models/Invoice.php
@@ -1147,17 +1147,18 @@ class Invoice extends EntityModel implements BalanceAffecting
         $invitation = $this->invitations[0];
         $link = $invitation->getLink('view', true);
         $pdfString = false;
+        $phantomjsSecret = env('PHANTOMJS_SECRET');
 
         try {
             if (env('PHANTOMJS_BIN_PATH')) {
-                $pdfString = CurlUtils::phantom('GET', $link . '?phantomjs=true&phantomjs_secret=' . env('PHANTOMJS_SECRET'));
+                $pdfString = CurlUtils::phantom('GET', $link . "?phantomjs=true&phantomjs_secret={$phantomjsSecret}");
             }
 
             if (! $pdfString && ($key = env('PHANTOMJS_CLOUD_KEY'))) {
                 if (Utils::isNinjaDev()) {
                     $link = env('TEST_LINK');
                 }
-                $url = "http://api.phantomjscloud.com/api/browser/v2/{$key}/?request=%7Burl:%22{$link}?phantomjs=true%22,renderType:%22html%22%7D";
+                $url = "http://api.phantomjscloud.com/api/browser/v2/{$key}/?request=%7Burl:%22{$link}?phantomjs=true&phantomjs_secret={$phantomjsSecret}%22,renderType:%22html%22%7D";
                 $pdfString = CurlUtils::get($url);
             }