diff --git a/webextensions/resources/group-tab.html b/webextensions/resources/group-tab.html
index fa80663c4..be3d8d869 100644
--- a/webextensions/resources/group-tab.html
+++ b/webextensions/resources/group-tab.html
@@ -116,6 +116,7 @@
   li.use-default-favicon .default-favicon,
   li.favicon-loading .default-favicon {
     background: var(--text-color);
+    break-inside: avoid; /* This is required to avoid unexpected slicing. See also: https://github.com/piroor/treestyletab/issues/3361 */
     display: inline-block;
     mask: url("./icons/defaultFavicon.svg") no-repeat center / 100%;
   }