diff --git a/CHANGELOG.md b/CHANGELOG.md
index ad2c0edf..a0e5da34 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,7 +7,8 @@
 * Translations updates.
 * Slovak translation integration.
 * Differenciate pt-PT and pt-BR translations.
-* Fix styling for "configure mod_firewall" button + Peertube v7.0.0 compatibility
+* Fix styling for "configure mod_firewall" button + Peertube v7.0.0 compatibility.
+* Fix #648: workaround for a regression in Firefox that breaks the scrollbar (Thanks [Raph](https://github.com/raphgilles) for the workaround!).
 
 ## 12.0.2
 
diff --git a/conversejs/custom/shared/styles/livechat.scss b/conversejs/custom/shared/styles/livechat.scss
index f5b5fbc5..d023e5c1 100644
--- a/conversejs/custom/shared/styles/livechat.scss
+++ b/conversejs/custom/shared/styles/livechat.scss
@@ -255,3 +255,12 @@ body.converse-embedded {
     }
   }
 }
+
+/* stylelint-disable-next-line no-duplicate-selectors */
+#conversejs {
+  converse-chat-content {
+    // Workaround for a regression in Firefox 136.
+    // See https://github.com/JohnXLivingston/peertube-plugin-livechat/issues/648
+    justify-content: normal !important;
+  }
+}