diff --git a/app/Importer/Importer.php b/app/Importer/Importer.php
index 45f7d1d170..381047a77a 100644
--- a/app/Importer/Importer.php
+++ b/app/Importer/Importer.php
@@ -119,10 +119,13 @@ abstract class Importer
         // Remove any custom fields that do not exist in the header row.  This prevents nulling out values that shouldn't exist.
         // In detail, we compare the lower case name of custom fields (indexed by name) to the keys in the header row.  This
         // results in an array with only custom fields that are in the file.
-        $this->customFields = array_intersect_key(
-            array_change_key_case($this->customFields),
-            array_change_key_case(array_flip($headerRow))
-        );
+        if ($this->customFields) {
+            $this->customFields = array_intersect_key(
+                array_change_key_case($this->customFields),
+                array_change_key_case(array_flip($headerRow))
+            );
+        }
+
 
 
         DB::transaction(function () use (&$results) {