diff --git a/app/extensions/extension_download.php b/app/extensions/extension_download.php
index 4dcac78e77..4bfad25831 100644
--- a/app/extensions/extension_download.php
+++ b/app/extensions/extension_download.php
@@ -132,7 +132,7 @@
 	}
 
 //get the extensions from the database and send them as output
-	if (is_array($_REQUEST["column_group"]) && @sizeof($_REQUEST["column_group"]) != 0) {
+	if (!empty($_REQUEST["column_group"]) && is_array($_REQUEST["column_group"]) && @sizeof($_REQUEST["column_group"]) != 0) {
 
 		//validate the token
 			$token = new token;
@@ -188,16 +188,16 @@
 	echo "<table class='list'>\n";
 	echo "<tr class='list-header'>\n";
 	echo "	<th class='checkbox'>\n";
-	echo "		<input type='checkbox' id='checkbox_all' name='checkbox_all' onclick='list_all_toggle();' ".($available_columns ?: "style='visibility: hidden;'").">\n";
+	echo "		<input type='checkbox' id='checkbox_all' name='checkbox_all' onclick='list_all_toggle();' ".(empty($available_columns) ? "style='visibility: hidden;'" : null).">\n";
 	echo "	</th>\n";
 	echo "	<th>".$text['label-column_name']."</th>\n";
 	echo "</tr>\n";
 
-	if (is_array($available_columns) && @sizeof($available_columns) != 0) {
+	if (!empty($available_columns) && is_array($available_columns) && @sizeof($available_columns) != 0) {
 		$x = 0;
 		foreach ($available_columns as $column_name) {
 			$list_row_onclick = "if (!this.checked) { document.getElementById('checkbox_all').checked = false; }";
-			echo "<tr class='list-row' href='".$list_row_url."'>\n";
+			echo "<tr class='list-row'>\n";
 			echo "	<td class='checkbox'>\n";
 			echo "		<input type='checkbox' name='column_group[]' id='checkbox_".$x."' value=\"".$column_name."\" onclick=\"".$list_row_onclick."\">\n";
 			echo "	</td>\n";
@@ -215,4 +215,4 @@
 //include the footer
 	require_once "resources/footer.php";
 
-?>
+?>
\ No newline at end of file