diff --git a/install.sh b/install.sh
index 2125025..0f48140 100755
--- a/install.sh
+++ b/install.sh
@@ -56,6 +56,10 @@ id "$ADMIN_USER" >/dev/null 2>&1 || die "ADMIN_USER $ADMIN_USER existiert nicht.
 
 install_base_packages() {
   log "Basispakete installieren"
+  # Heal keyrings created by an older installer run under this script's 0077
+  # umask before apt attempts to refresh any already configured repositories.
+  [[ ! -e /usr/share/keyrings/nvidia-container-toolkit-keyring.gpg ]] || \
+    chmod 0644 /usr/share/keyrings/nvidia-container-toolkit-keyring.gpg
   apt-get update
   DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
     ca-certificates curl git gnupg jq openssl wireguard-tools iptables \