diff --git a/src/renderer/src/App.tsx b/src/renderer/src/App.tsx
index 9e7e4e8e..1805ed43 100644
--- a/src/renderer/src/App.tsx
+++ b/src/renderer/src/App.tsx
@@ -61,7 +61,7 @@ import {
   mapRecommendedDefaultFormat,
   getFfCommandLine,
 } from './ffmpeg';
-import { shouldCopyStreamByDefault, getAudioStreams, getRealVideoStreams, isAudioDefinitelyNotSupported, willPlayerProperlyHandleVideo, doesPlayerSupportHevcPlayback, getSubtitleStreams, enableVideoTrack, enableAudioTrack, canHtml5PlayerPlayStreams } from './util/streams';
+import { shouldCopyStreamByDefault, getAudioStreams, getRealVideoStreams, isAudioDefinitelyNotSupported, willPlayerProperlyHandleVideo, doesPlayerSupportHevcPlayback, getSubtitleStreams, enableVideoTrack, enableAudioTrack, canHtml5PlayerPlayStreams, isMatroska } from './util/streams';
 import { exportEdlFile, readEdlFile, loadLlcProject, askForEdlImport } from './edlStore';
 import { formatYouTube, getFrameCountRaw, formatTsvHuman } from './edlFormats';
 import {
@@ -83,7 +83,7 @@ import { askForHtml5ifySpeed } from './dialogs/html5ify';
 import { askForOutDir, askForImportChapters, promptTimecode, askForFileOpenAction, confirmExtractAllStreamsDialog, showCleanupFilesDialog, showDiskFull, showExportFailedDialog, showConcatFailedDialog, openYouTubeChaptersDialog, showRefuseToOverwrite, openDirToast, openExportFinishedToast, openConcatFinishedToast, showOpenDialog, showMuxNotSupported, promptDownloadMediaUrl, CleanupChoicesType, showOutputNotWritable } from './dialogs';
 import { openSendReportDialog } from './reporting';
 import { fallbackLng } from './i18n';
-import { sortSegments, convertSegmentsToChapters, hasAnySegmentOverlap, isDurationValid, getPlaybackAction, getSegmentTags, filterNonMarkers } from './segments';
+import { sortSegments, convertSegmentsToChaptersWithGaps, hasAnySegmentOverlap, isDurationValid, getPlaybackAction, getSegmentTags, filterNonMarkers } from './segments';
 import { generateOutSegFileNames as generateOutSegFileNamesRaw, generateMergedFileNames as generateMergedFileNamesRaw, defaultOutSegTemplate, defaultCutMergedFileTemplate } from './util/outputNameTemplate';
 import { rightBarWidth, leftBarWidth, ffmpegExtractWindow, zoomMax } from './util/constants';
 import BigWaveform from './components/BigWaveform';
@@ -443,7 +443,7 @@ function App() {
     setRotation((r) => (r + 90) % 450);
     setHideMediaSourcePlayer(false);
     // Matroska is known not to work, so we warn user. See https://github.com/mifi/lossless-cut/discussions/661
-    const supportsRotation = !(fileFormat != null && ['matroska', 'webm'].includes(fileFormat));
+    const supportsRotation = !isMatroska(fileFormat);
     if (!supportsRotation) showNotification({ text: i18n.t('Lossless rotation might not work with this file format. You may try changing to MP4') });
   }, [fileFormat, showNotification]);
 
@@ -1085,7 +1085,8 @@ function App() {
           errorToast(i18n.t('Make sure you have no overlapping segments.'));
           return;
         }
-        chaptersToAdd = convertSegmentsToChapters(sortedSegments);
+        // matroska supports gaps, so we can use segments directly
+        chaptersToAdd = isMatroska(fileFormat) ? sortedSegments : convertSegmentsToChaptersWithGaps(sortedSegments);
       }
 
       console.log('outSegTemplateOrDefault', outSegTemplateOrDefault);
diff --git a/src/renderer/src/segments.test.ts b/src/renderer/src/segments.test.ts
index 8e96c53f..66457271 100644
--- a/src/renderer/src/segments.test.ts
+++ b/src/renderer/src/segments.test.ts
@@ -1,9 +1,9 @@
 import { test, it, expect, describe } from 'vitest';
 
-import { convertSegmentsToChapters, partitionIntoOverlappingRanges, formatSegNum, combineOverlappingSegments, invertSegments } from './segments';
+import { convertSegmentsToChaptersWithGaps, partitionIntoOverlappingRanges, formatSegNum, combineOverlappingSegments, invertSegments } from './segments';
 
 it('converts segments to chapters with gaps', () => {
-  expect(convertSegmentsToChapters([
+  expect(convertSegmentsToChaptersWithGaps([
     {
       start: 104.612,
       end: 189.053,
@@ -27,8 +27,8 @@ it('converts segments to chapters with gaps', () => {
   ])).toMatchSnapshot();
 });
 
-it('converts segments to chapters with no gaps', () => {
-  expect(convertSegmentsToChapters([
+it('converts segments to chapters with no gaps when adjacent', () => {
+  expect(convertSegmentsToChaptersWithGaps([
     {
       start: 0,
       end: 2,
@@ -43,7 +43,7 @@ it('converts segments to chapters with no gaps', () => {
 });
 
 it('converts segments to chapters with single long segment', () => {
-  expect(convertSegmentsToChapters([
+  expect(convertSegmentsToChaptersWithGaps([
     {
       start: 0,
       end: 1,
diff --git a/src/renderer/src/segments.ts b/src/renderer/src/segments.ts
index 2a39bd79..4ab51224 100644
--- a/src/renderer/src/segments.ts
+++ b/src/renderer/src/segments.ts
@@ -4,7 +4,7 @@ import minBy from 'lodash/minBy';
 import maxBy from 'lodash/maxBy';
 import invariant from 'tiny-invariant';
 
-import { PlaybackMode, SegmentBase, SegmentTags, SegmentToExport, StateSegment } from './types';
+import { DefiniteSegmentBase, PlaybackMode, SegmentBase, SegmentTags, SegmentToExport, StateSegment } from './types';
 
 
 export const isDurationValid = (duration?: number): duration is number => duration != null && Number.isFinite(duration) && duration > 0;
@@ -208,19 +208,16 @@ export function invertSegments(
   return ret.filter(({ start, end }) => end == null || end > start);
 }
 
-// because chapters need to be contiguous, we need to insert gaps in-between
-export function convertSegmentsToChapters(sortedSegments: { start: number, end: number, name?: string | undefined }[]) {
-  if (sortedSegments.length === 0) return [];
-  if (hasAnySegmentOverlap(sortedSegments)) throw new Error('Segments cannot overlap');
-
+// because chapters need to be contiguous in formats like MP4, we insert "gap" segments in-between, so that end times will be correct
+export function convertSegmentsToChaptersWithGaps(sortedSegments: (DefiniteSegmentBase & { name?: string | undefined })[]) {
   // eslint-disable-next-line @typescript-eslint/no-unused-vars
-  const invertedSegments = invertSegments(sortedSegments, true, false).map(({ end, name: _ignored, ...seg }) => {
+  const invertedSegmentsWithoutName = invertSegments(sortedSegments, true, false).map(({ end, name: _ignored, ...seg }) => {
     invariant(end != null); // to please typescript
     return { ...seg, end };
   });
 
   // inverted segments will be "gap" segments. Merge together with normal segments
-  return sortSegments([...sortedSegments, ...invertedSegments]);
+  return sortSegments([...sortedSegments, ...invertedSegmentsWithoutName]);
 }
 
 export function getPlaybackAction({ playbackMode, currentTime, playingSegment }: {
diff --git a/src/renderer/src/util/streams.ts b/src/renderer/src/util/streams.ts
index 59ee3f6d..1f61a7d5 100644
--- a/src/renderer/src/util/streams.ts
+++ b/src/renderer/src/util/streams.ts
@@ -101,6 +101,8 @@ export function getActiveDisposition(disposition: FFprobeStreamDisposition | und
 
 export const isMov = (format: string | undefined) => format != null && ['ismv', 'ipod', 'mp4', 'mov'].includes(format);
 
+export const isMatroska = (format: string | undefined) => format != null && ['matroska', 'webm'].includes(format);
+
 type GetVideoArgsFn = (a: { streamIndex: number, outputIndex: number }) => string[] | undefined;
 
 function getPerStreamFlags({ stream, outputIndex, outFormat, manuallyCopyDisposition = false, getVideoArgs = () => undefined, areWeCutting }: {