diff --git a/cgi-updater-payload.sh b/cgi-updater-payload.sh
index 1a4d7be..677cea8 100755
--- a/cgi-updater-payload.sh
+++ b/cgi-updater-payload.sh
@@ -21,7 +21,9 @@ ubuntu_install_r_cran () {
 # https://cran.r-project.org/bin/linux/ubuntu/
 deb https://cran.fhcrc.org/bin/linux/ubuntu $(lsb_release -cs)/
 EOF
-    apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E084DAB9
+    local key=E084DAB9
+    grep -q $key <( apt-key list ) ||
+	apt-key adv --keyserver keyserver.ubuntu.com --recv-keys $key
     apt-get update
     apt-get -y install r-base-dev
 }