diff --git a/src/Form/AddSectionToLibraryForm.php b/src/Form/AddSectionToLibraryForm.php
index 8d3ea25150e6207a67993c5f579ed5cd5eb582f2..b08ceec85b4bc825353e5092e306f57110e0b743 100644
--- a/src/Form/AddSectionToLibraryForm.php
+++ b/src/Form/AddSectionToLibraryForm.php
@@ -121,7 +121,7 @@ class AddSectionToLibraryForm extends FormBase {
       '#multiple' => FALSE,
       '#upload_location' => 'public://',
       '#upload_validators' => [
-        'file_validate_extensions' => ['gif png jpg jpeg'],
+        'FileExtension' => ['gif png jpg jpeg'],
       ],
     ];
 
diff --git a/src/Form/AddTemplateToLibraryForm.php b/src/Form/AddTemplateToLibraryForm.php
index 3dadc186d360073d27cb3a71f58cb9d000bbb9d0..6863346b24ecb667a25d06351ab90edb26c4a66b 100644
--- a/src/Form/AddTemplateToLibraryForm.php
+++ b/src/Form/AddTemplateToLibraryForm.php
@@ -121,7 +121,7 @@ class AddTemplateToLibraryForm extends FormBase {
       '#multiple' => FALSE,
       '#upload_location' => 'public://',
       '#upload_validators' => [
-        'file_validate_extensions' => ['gif png jpg jpeg'],
+        'FileExtension' => ['gif png jpg jpeg'],
       ],
     ];