diff --git a/code/GroupImportForm.php b/code/GroupImportForm.php
index a514247d..d139bc2c 100644
--- a/code/GroupImportForm.php
+++ b/code/GroupImportForm.php
@@ -45,7 +45,7 @@ class GroupImportForm extends Form {
 					)
 				)
 			);
-			$fileField->setAllowedExtensions(array('csv'));
+			$fileField->getValidator()->setAllowedExtensions(array('csv'));
 		}
 		
 		if(!$actions) $actions = new FieldSet(
diff --git a/code/MemberImportForm.php b/code/MemberImportForm.php
index d3df83c5..c1a30525 100644
--- a/code/MemberImportForm.php
+++ b/code/MemberImportForm.php
@@ -44,7 +44,7 @@ class MemberImportForm extends Form {
 					)
 				)
 			);
-			$fileField->setAllowedExtensions(array('csv'));
+			$fileField->getValidator()->setAllowedExtensions(array('csv'));
 		}
 		
 		if(!$actions) $actions = new FieldSet(