diff --git a/code/MemberTableField.php b/code/MemberTableField.php
index 8f150a9d..02d36e21 100755
--- a/code/MemberTableField.php
+++ b/code/MemberTableField.php
@@ -414,6 +414,7 @@ class MemberTableField_Popup extends ComplexTableField_Popup {
 	function forTemplate() {
 		$ret = parent::forTemplate();
 		
+		Requirements::css(CMS_DIR . '/css/SecurityAdmin.css');
 		Requirements::javascript(CMS_DIR . '/javascript/MemberTableField.js');
 		Requirements::javascript(CMS_DIR . '/javascript/MemberTableField_popup.js');
 		
diff --git a/css/SecurityAdmin.css b/css/SecurityAdmin.css
index efb9c2b1..90a30cea 100644
--- a/css/SecurityAdmin.css
+++ b/css/SecurityAdmin.css
@@ -5,4 +5,10 @@
 
 #Form_EditForm_Permissions .Arg input {
 	text-align: right;
+}
+
+/* Ensure there's enough room in the tab for TreeMultiSelectField expansion */
+#MemberTableField_Popup_DetailForm #Groups,
+#MemberTableField_Popup_AddForm #Groups {
+	height: 250px;
 }
\ No newline at end of file