diff --git a/model/DataObject.php b/model/DataObject.php
index 992461c5d..bba75577c 100644
--- a/model/DataObject.php
+++ b/model/DataObject.php
@@ -3709,13 +3709,18 @@ class DataObject extends ViewableData implements DataObjectInterface, i18nEntity
 	 * @return array
 	 */
 	public function summaryFields() {
-		$fields = $this->stat('summary_fields');
+		$rawFields = $this->stat('summary_fields');
 
-		// if fields were passed in numeric array,
-		// convert to an associative array
-		if($fields && array_key_exists(0, $fields)) {
-			$fields = array_combine(array_values($fields), array_values($fields));
-		}
+		$fields = [];
+        // Merge associative / numeric keys
+        if (is_array($rawFields)) {
+	        foreach ($rawFields as $key => $value) {
+	            if (is_int($key)) {
+	                $key = $value;
+	            }
+	            $fields[$key] = $value;
+	        }
+    	}
 
 		if (!$fields) {
 			$fields = array();