diff --git wp-admin/theme-editor.php wp-admin/theme-editor.php
index c9adabe0cd4b21a289efc727a0b59afd912bfca9..f64e20c9dffaadcbc8d7df6dccbb65d26303ce7f 100644
--- wp-admin/theme-editor.php
+++ wp-admin/theme-editor.php
@@ -62,7 +62,7 @@ $allowed_files = $theme->get_files( 'php', 1 );
 $has_templates = ! empty( $allowed_files );
 $style_files = $theme->get_files( 'css' );
 $allowed_files['style.css'] = $style_files['style.css'];
-$allowed_files += $style_files;
+$allowed_files += apply_filters( 'wp_theme_editor_filetypes', $style_files, $theme );
 
 if ( empty( $file ) ) {
 	$relative_file = 'style.css';