diff --git a/lib/widgets/rename_dialog.dart b/lib/widgets/rename_dialog.dart
index 266c9c47..848c7946 100644
--- a/lib/widgets/rename_dialog.dart
+++ b/lib/widgets/rename_dialog.dart
@@ -2,6 +2,7 @@ import 'dart:io';
 
 import 'package:flutter/material.dart';
 import 'package:path/path.dart';
+import 'package:path/path.dart' as p;
 
 class RenameDialog extends StatefulWidget {
   final String oldPath;
@@ -42,6 +43,10 @@ class _RenameDialogState extends State<RenameDialog> {
                 return 'Please enter a name';
               }
 
+              if (value.contains(p.separator)) {
+                return 'Cannot contain ${p.separator}';
+              }
+
               var newPath = join(dirname(widget.oldPath), value);
               if (FileSystemEntity.typeSync(newPath) !=
                   FileSystemEntityType.notFound) {