diff --git a/src/controller/audio-stream-controller.js b/src/controller/audio-stream-controller.js
index a4c2141aa02..e46f6e55335 100644
--- a/src/controller/audio-stream-controller.js
+++ b/src/controller/audio-stream-controller.js
@@ -645,7 +645,7 @@ class AudioStreamController extends TaskLoop {
         data.endDTS = data.startDTS + fragCurrent.duration;
       }
 
-      fragCurrent.elementaryStreams.add(data.type);
+      fragCurrent.addElementaryStream(data.type);
 
       logger.log(`parsed ${data.type},PTS:[${data.startPTS.toFixed(3)},${data.endPTS.toFixed(3)}],DTS:[${data.startDTS.toFixed(3)}/${data.endDTS.toFixed(3)}],nb:${data.nb}`);
       LevelHelper.updateFragPTSDTS(track.details,fragCurrent,data.startPTS,data.endPTS);
diff --git a/src/controller/stream-controller.js b/src/controller/stream-controller.js
index 73cdec1f841..2b06f14c97b 100644
--- a/src/controller/stream-controller.js
+++ b/src/controller/stream-controller.js
@@ -1090,7 +1090,7 @@ class StreamController extends TaskLoop {
         data.endDTS = data.startDTS + fragCurrent.duration;
       }
 
-      frag.elementaryStreams.add(data.type);
+      frag.addElementaryStream(data.type);
 
       logger.log(`Parsed ${data.type},PTS:[${data.startPTS.toFixed(3)},${data.endPTS.toFixed(3)}],DTS:[${data.startDTS.toFixed(3)}/${data.endDTS.toFixed(3)}],nb:${data.nb},dropped:${data.dropped || 0}`);
 
diff --git a/src/helper/fragment-tracker.js b/src/helper/fragment-tracker.js
index 8a4ae7673e1..c17053e306b 100644
--- a/src/helper/fragment-tracker.js
+++ b/src/helper/fragment-tracker.js
@@ -69,7 +69,7 @@ export class FragmentTracker extends EventHandler {
     let fragmentEntity = this.fragments.get(fragKey);
     fragmentEntity.buffered = true;
     for (let [elementaryStream, timeRange] of this.timeRanges) {
-      if(fragment.elementaryStreams.has(elementaryStream) === true) {
+      if(fragment.hasElementaryStream(elementaryStream) === true) {
         // Check for malformed fragments
         // Gaps need to be calculated for each elementaryStream
         fragmentEntity.range[elementaryStream] = this.getBufferedTimes(fragment.startPTS, fragment.endPTS, timeRange);
diff --git a/src/loader/fragment.js b/src/loader/fragment.js
index a8e7fcc3e84..4eaa11d8cdf 100644
--- a/src/loader/fragment.js
+++ b/src/loader/fragment.js
@@ -11,8 +11,9 @@ export default class Fragment {
     this._decryptdata = null;
     this.tagList = [];
 
-    // Set is used because the elements do not repeat
-    this.elementaryStreams = new Set();
+    // Holds the type of data this fragment contains(eg. video/audio)
+    // Set is used because the elements should not repeat
+    this._elementaryStreams = new Set();
   }
 
   get url() {
@@ -72,6 +73,17 @@ export default class Fragment {
     return this._decryptdata;
   }
 
+  /**
+   * @param {ElementaryStreamType}
+   */
+  addElementaryStream(type) {
+    this._elementaryStreams.add(type);
+  }
+
+  hasElementaryStream(type) {
+    return this._elementaryStreams.has(type) === true;
+  }
+
   /**
    * Utility method for parseLevelPlaylist to create an initialization vector for a given segment
    * @returns {Uint8Array}
diff --git a/tests/unit/helper/fragment-tracker.js b/tests/unit/helper/fragment-tracker.js
index eae2ddb199c..8712517f0b6 100644
--- a/tests/unit/helper/fragment-tracker.js
+++ b/tests/unit/helper/fragment-tracker.js
@@ -13,6 +13,14 @@ function createMockBuffer(buffered) {
   };
 }
 
+function createMockFragment(data, types) {
+  data._elementaryStreams = new Set(types);
+  data.hasElementaryStream = (type) => {
+    return data._elementaryStreams.has(type) === true;
+  }
+  return data;
+}
+
 describe('FragmentTracker', () => {
   describe('getPartialFragment', () => {
     let hls, fragmentTracker, fragment, buffered, partialFragment, timeRanges;
@@ -20,14 +28,14 @@ describe('FragmentTracker', () => {
     hls = new Hls({});
     fragmentTracker = new FragmentTracker(hls);
 
-    fragment = {
+    fragment = createMockFragment({
       startPTS: 0,
       endPTS: 1,
       sn: 1,
       level: 1,
-      elementaryStreams: new Set(['audio', 'video']),
       type: 'main'
-    };
+    }, ['audio', 'video']);
+
     hls.trigger(Event.FRAG_LOADED, { frag: fragment });
 
     buffered = createMockBuffer([
@@ -67,14 +75,13 @@ describe('FragmentTracker', () => {
 
 
     let addFragment = () => {
-      fragment = {
+      fragment = createMockFragment({
         startPTS: 0,
         endPTS: 1,
         sn: 1,
         level: 0,
-        elementaryStreams: new Set(['audio', 'video']),
         type: 'main'
-      };
+      }, ['audio', 'video']);
       hls.trigger(Event.FRAG_LOADED, { frag: fragment });
     };
 
@@ -160,14 +167,13 @@ describe('FragmentTracker', () => {
     fragmentTracker = new FragmentTracker(hls);
 
     it('supports audio buffer', () => {
-      fragment = {
+      fragment = createMockFragment({
         startPTS: 0,
         endPTS: 1,
         sn: 1,
         level: 1,
-        elementaryStreams: new Set(['audio', 'video']),
         type: 'main'
-      };
+      }, ['audio', 'video']);
       hls.trigger(Event.FRAG_LOADED, { frag: fragment });
 
       timeRanges = new Map();
@@ -191,14 +197,13 @@ describe('FragmentTracker', () => {
     });
 
     it('supports video buffer', () => {
-      fragment = {
+      fragment = createMockFragment({
         startPTS: 0,
         endPTS: 1,
         sn: 1,
         level: 1,
-        elementaryStreams: new Set(['audio', 'video']),
         type: 'main'
-      };
+      }, ['audio', 'video']);
       hls.trigger(Event.FRAG_LOADED, { frag: fragment });
 
       timeRanges = new Map();
@@ -222,14 +227,13 @@ describe('FragmentTracker', () => {
     });
 
     it('supports audio only buffer', () => {
-      fragment = {
+      fragment = createMockFragment({
         startPTS: 0,
         endPTS: 1,
         sn: 1,
         level: 1,
-        elementaryStreams: new Set(['audio']),
         type: 'audio'
-      };
+      }, ['audio']);
       hls.trigger(Event.FRAG_LOADED, { frag: fragment });
 
       timeRanges = new Map();