diff --git a/setup.sh b/setup.sh
index 06bca69..8437f72 100755
--- a/setup.sh
+++ b/setup.sh
@@ -541,9 +541,10 @@ install_category_pkgs() {
                 [[ "$item" == *libvirt* || "$item" == *virt-manager* || "$item" == *virt-install* ]] && wants_libvirt=true
             done
             if $wants_libvirt; then
-                info "Enabling libvirtd and adding $USER to the libvirt group..."
+                local real_user="${SUDO_USER:-$USER}"
+                info "Enabling libvirtd and adding $real_user to the libvirt group..."
                 sudo systemctl enable --now libvirtd 2>/dev/null || true
-                sudo usermod -aG libvirt "$USER" || true
+                sudo usermod -aG libvirt "$real_user" || true
                 warn "libvirt group membership applies after re-login."
             fi
             ;;