diff --git a/domain/duration.py b/domain/duration.py
index 64d7acc..5ed8d91 100644
--- a/domain/duration.py
+++ b/domain/duration.py
@@ -60,7 +60,7 @@ def normalizeToFullPositionStr(positionStr):
     if m3 is not None:
         return millisecondsToPositionStr(int(m3.group(1)) * 1000 * 60 * 60 + int(m3.group(2)) * 1000 * 60 + int(m3.group(3)) * 1000)
     # end if
-    m4 = re.match(r"^(\d+):(\d+):(\d+)\.(\d+)$", positionStr)
+    m4 = re.match(r"^(\d+):(\d+):(\d+)\.(\d{1,3})$", positionStr)
     if m4 is not None:
         return positionStr
     #end if
diff --git a/test/domain_test/testDuration.py b/test/domain_test/testDuration.py
index 3e1214e..cdf0352 100644
--- a/test/domain_test/testDuration.py
+++ b/test/domain_test/testDuration.py
@@ -52,4 +52,5 @@ def test_normalizeToFullPositionStr(self):
         self.assertEqual(domain.normalizeToFullPositionStr("01:00:00"), "01:00:00.000")
         self.assertEqual(domain.normalizeToFullPositionStr("01:01:01"), "01:01:01.000")
         self.assertEqual(domain.normalizeToFullPositionStr("00:00:00.000"), "00:00:00.000")
+        self.assertRaises(ValueError, domain.normalizeToFullPositionStr, "00:00:13.4444")
         self.assertRaises(ValueError, domain.normalizeToFullPositionStr, "aaaa")