diff --git a/Emby.Server.Implementations/Chapters/ChapterManager.cs b/Emby.Server.Implementations/Chapters/ChapterManager.cs
index f24c975c14..a2d7d7d7fb 100644
--- a/Emby.Server.Implementations/Chapters/ChapterManager.cs
+++ b/Emby.Server.Implementations/Chapters/ChapterManager.cs
@@ -108,7 +108,7 @@ public class ChapterManager : IChapterManager
             sum += chapters[i].StartPositionTicks - chapters[i - 1].StartPositionTicks;
         }
 
-        return sum / (chapters.Count - 1);
+        return sum / chapters.Count;
     }
 
     /// <inheritdoc />
diff --git a/tests/Jellyfin.Providers.Tests/MediaInfo/FFProbeVideoInfoTests.cs b/tests/Jellyfin.Providers.Tests/MediaInfo/FFProbeVideoInfoTests.cs
index 7cb3e61724..a7491f42e9 100644
--- a/tests/Jellyfin.Providers.Tests/MediaInfo/FFProbeVideoInfoTests.cs
+++ b/tests/Jellyfin.Providers.Tests/MediaInfo/FFProbeVideoInfoTests.cs
@@ -59,4 +59,20 @@ public class FFProbeVideoInfoTests
 
         Assert.Equal(chaptersCount, chapters.Length);
     }
+
+    [Theory]
+    [InlineData(1L)]
+    [InlineData(TimeSpan.TicksPerMinute * 3)]
+    [InlineData(TimeSpan.TicksPerMinute * 5)]
+    [InlineData((TimeSpan.TicksPerMinute * 5) + 1)]
+    [InlineData((TimeSpan.TicksPerMinute * 50) + 1)]
+    public void CreateDummyChapters_PositiveRuntime_NoChapterBeyondRuntime(long runtime)
+    {
+        var chapters = _fFProbeVideoInfo.CreateDummyChapters(new Video()
+                {
+                    RunTimeTicks = runtime
+                });
+
+        Assert.All(chapters, chapter => Assert.True(chapter.StartPositionTicks < runtime));
+    }
 }