diff --git a/libse/Paragraph.cs b/libse/Paragraph.cs
index b33f5c91b..4e5daac4a 100644
--- a/libse/Paragraph.cs
+++ b/libse/Paragraph.cs
@@ -115,11 +115,8 @@ namespace Nikse.SubtitleEdit.Core
             if (StartTime.IsMaxTime)
                 return;
 
-            double seconds = StartTime.TimeSpan.TotalSeconds * factor + adjustmentInSeconds;
-            StartTime.TimeSpan = TimeSpan.FromSeconds(seconds);
-
-            seconds = EndTime.TimeSpan.TotalSeconds * factor + adjustmentInSeconds;
-            EndTime.TimeSpan = TimeSpan.FromSeconds(seconds);
+            StartTime.TotalMilliseconds = StartTime.TotalMilliseconds * factor + (adjustmentInSeconds * TimeCode.BaseUnit);
+            EndTime.TotalMilliseconds = EndTime.TotalMilliseconds * factor + (adjustmentInSeconds * TimeCode.BaseUnit);
         }
 
         public void CalculateFrameNumbersFromTimeCodes(double frameRate)
diff --git a/src/Test/Logic/ParagraphTest.cs b/src/Test/Logic/ParagraphTest.cs
index 41adb9cac..10f01de2a 100644
--- a/src/Test/Logic/ParagraphTest.cs
+++ b/src/Test/Logic/ParagraphTest.cs
@@ -38,17 +38,19 @@ namespace Test.Logic
         [TestMethod]
         public void TestAdjust1()
         {
-            var p = new Paragraph { Text = string.Empty, StartTime = new TimeCode(0,1,1,1) };
+            var p = new Paragraph { Text = string.Empty, StartTime = new TimeCode(0,1,1,1), EndTime = new TimeCode(0, 1, 3, 1) };
             p.Adjust(1, 10);
-            Assert.AreEqual(new TimeCode(0,1,11,1).TotalMilliseconds, p.StartTime.TotalMilliseconds);
+            Assert.AreEqual(new TimeCode(0, 1, 11, 1).TotalMilliseconds, p.StartTime.TotalMilliseconds);
+            Assert.AreEqual(new TimeCode(0, 1, 13, 1).TotalMilliseconds, p.EndTime.TotalMilliseconds);
         }
 
         [TestMethod]
         public void TestAdjust2()
         {
-            var p = new Paragraph { Text = string.Empty, StartTime = new TimeCode(0, 1, 1, 1) };
+            var p = new Paragraph { Text = string.Empty, StartTime = new TimeCode(0, 1, 1, 1), EndTime = new TimeCode(0, 1, 4, 1) };
             p.Adjust(2, 10);
             Assert.AreEqual(new TimeCode(0, 2, 12, 2).TotalMilliseconds, p.StartTime.TotalMilliseconds);
+            Assert.AreEqual(new TimeCode(0, 2, 18, 2).TotalMilliseconds, p.EndTime.TotalMilliseconds);
         }
 
         [TestMethod]
@@ -59,5 +61,12 @@ namespace Test.Logic
             Assert.AreEqual(1, p.StartTime.TotalSeconds);
         }
 
+        [TestMethod]
+        public void TestDuration()
+        {
+            var p = new Paragraph { Text = string.Empty, StartTime = new TimeCode(0, 1, 0, 0), EndTime =  new TimeCode(0, 1, 1, 1) };
+            Assert.AreEqual(p.Duration.TotalMilliseconds, 1001);
+        }
+
     }
 }