diff --git a/core/core.func b/core/core.func
index 17f5ffa..f4faa6f 100644
--- a/core/core.func
+++ b/core/core.func
@@ -2490,7 +2490,8 @@ cleanup_lxc() {
     rm -rf /root/.npm/_cacache /root/.npm/_logs 2>/dev/null || true
   fi
   if command -v yarn &>/dev/null; then
-    rm -rf /root/.cache/yarn /root/.yarn/cache 2>/dev/null || true
+    # yarn 1 run as root caches under /usr/local/share, not in $HOME
+    rm -rf /root/.cache/yarn /root/.yarn/cache /root/.yarn/berry/cache /usr/local/share/.cache/yarn 2>/dev/null || true
   fi
   if command -v pnpm &>/dev/null; then
     pnpm store prune &>/dev/null || true
diff --git a/tests/install-cleanup.sh b/tests/install-cleanup.sh
index c19d4dc..0397c76 100644
--- a/tests/install-cleanup.sh
+++ b/tests/install-cleanup.sh
@@ -67,5 +67,7 @@ result=$(
 check "no apt-get: cleanup_lxc cleans through pkg_clean" "pkg_clean" "$result"
 check "install.func does not shadow core.func's cleanup_lxc" "" "$(grep -n '^cleanup_lxc()' "$CORE_DIR/lxc/install.func" || true)"
 
+check "cleanup_lxc clears yarn 1's root cache" "1" "$(declare -f cleanup_lxc | grep -c '/usr/local/share/.cache/yarn')"
+
 printf '%s passed, %s failed\n' "$passed" "$failed"
 ((failed == 0))