diff --git a/lib/src/io/vm.dart b/lib/src/io/vm.dart
index c13991672..aa5eaf064 100644
--- a/lib/src/io/vm.dart
+++ b/lib/src/io/vm.dart
@@ -74,7 +74,7 @@ void ensureDir(String path) => io.Directory(path).createSync(recursive: true);
 Iterable<String> listDir(String path, {bool recursive = false}) =>
     io.Directory(path)
         .listSync(recursive: recursive)
-        .where((entity) => entity is io.File)
+        .whereType<io.File>()
         .map((entity) => entity.path);
 
 DateTime modificationTime(String path) {