diff --git a/lib/media/content_workarounds.js b/lib/media/content_workarounds.js
index c47ff7f05c..1a4d4b81a3 100644
--- a/lib/media/content_workarounds.js
+++ b/lib/media/content_workarounds.js
@@ -81,6 +81,12 @@ shaka.media.ContentWorkarounds = class {
             newType: ContentWorkarounds.BOX_TYPE_ENCV_,
           });
         })
+        .fullBox('ac-3', (box) => {
+          boxesToModify.push({
+            box,
+            newType: ContentWorkarounds.BOX_TYPE_ENCA_,
+          });
+        })
         .fullBox('ec-3', (box) => {
           boxesToModify.push({
             box,