diff --git a/src/wp-admin/includes/class-wp-list-table.php b/src/wp-admin/includes/class-wp-list-table.php
index 2e5c10df1c..641e863475 100644
--- a/src/wp-admin/includes/class-wp-list-table.php
+++ b/src/wp-admin/includes/class-wp-list-table.php
@@ -850,8 +850,16 @@ class WP_List_Table {
 	 * @return array
 	 */
 	protected function get_column_info() {
-		if ( isset( $this->_column_headers ) && is_array( $this->_column_headers ) && count( $this->_column_headers ) >= 4 ) {
-			return $this->_column_headers;
+		// $_column_headers is already set / cached
+		if ( isset( $this->_column_headers ) && is_array( $this->_column_headers ) ) {
+			// Back-compat for list tables that have been manually setting $_column_headers for horse reasons.
+			// In 4.3, we added a fourth argument for primary column.
+			$column_headers = array( array(), array(), array(), '' );
+			foreach ( $this->_column_headers as $key => $value ) {
+				$column_headers[ $key ] = $value;
+			}
+
+			return $column_headers;
 		}
 
 		$columns = get_column_headers( $this->screen );