diff --git a/lib/ozzie.dart b/lib/ozzie.dart
index 244162f..b446375 100644
--- a/lib/ozzie.dart
+++ b/lib/ozzie.dart
@@ -123,7 +123,8 @@ class Ozzie {
 
   String get _groupFolderName => '$rootFolderName/$groupName';
 
-  String get _timestamp => DateTime.now().toIso8601String();
+  String get _timestamp =>
+      DateTime.now().toIso8601String().replaceAll(':', '.');
 
   String _fileName(String screenshotName) => '$_timestamp-$screenshotName.png';
 
diff --git a/test/ozzie_test.dart b/test/ozzie_test.dart
index 7e471cc..08426d2 100644
--- a/test/ozzie_test.dart
+++ b/test/ozzie_test.dart
@@ -90,6 +90,16 @@ void main() {
         expect(true, resultFile.path.contains('rim.png'));
       });
 
+      test('takeScreenshot generates PNGs don`t contains character ":" on name',
+          () async {
+        await ozzie.takeScreenshot('character');
+        final files =
+            Directory('$rootFolderName/$testGroupName').listSync().toList();
+        final resultFile =
+            files.where((f) => f is File).map((f) => f as File).first;
+        expect(false, resultFile.path.contains(':'));
+      });
+
       group('HTML report generation', () {
         test('not calling generateHtmlReport does not create index.html',
             () async {