diff --git a/core/Plugin/Report.php b/core/Plugin/Report.php
index af61a33a0a45f5a45f8b67d205c3a67b7eb69fb9..5f959864cb342abc7290f0c2f3983853f799c756 100644
--- a/core/Plugin/Report.php
+++ b/core/Plugin/Report.php
@@ -405,7 +405,7 @@ class Report
      * default metric translation for this metric using the {@hook Metrics.getDefaultMetricTranslations} event. If you
      * want to overwrite any default metric translation you should overwrite this method, call this parent method to
      * get all default translations and overwrite any custom metric translations.
-     * @return array
+     * @return array|mixed
      * @api
      */
     public function getProcessedMetrics()
diff --git a/plugins/API/Reports/Get.php b/plugins/API/Reports/Get.php
index 11a4df5d6a595b06406f001202b2c01d583c204a..de087d0a8633296ecbdde3c56059a2eaa5e97375 100644
--- a/plugins/API/Reports/Get.php
+++ b/plugins/API/Reports/Get.php
@@ -67,7 +67,10 @@ class Get extends Report
     {
         $processedMetrics = array();
         foreach ($this->reportsToMerge as $report) {
-            $processedMetrics = array_merge($processedMetrics, $report->getProcessedMetrics());
+            $reportMetrics = $report->getProcessedMetrics();
+            if (is_array($reportMetrics)) {
+                $processedMetrics = array_merge($processedMetrics, $reportMetrics);
+            }
         }
         return $processedMetrics;
     }