diff --git a/optional/traefik-certdumper/run.sh b/optional/traefik-certdumper/run.sh
index eeb45ac0..2880d44f 100755
--- a/optional/traefik-certdumper/run.sh
+++ b/optional/traefik-certdumper/run.sh
@@ -5,8 +5,10 @@ function dump() {
 
     traefik-certs-dumper file --crt-name "cert" --crt-ext ".pem" --key-name "key" --key-ext ".pem" --domain-subdir --dest /tmp/work --source /traefik/acme.json > /dev/null
 
-    if diff -q /tmp/work/${DOMAIN}/cert.pem /output/cert.pem >/dev/null && \
-	    diff -q /tmp/work/${DOMAIN}/key.pem /output/key.pem >/dev/null ; then
+    if [[ -f /tmp/work/${DOMAIN}/cert.pem && -f /tmp/work/${DOMAIN}/key.pem && -f /output/cert.pem && -f /output/key.pem ]] && \
+	diff -q /tmp/work/${DOMAIN}/cert.pem /output/cert.pem >/dev/null && \
+	diff -q /tmp/work/${DOMAIN}/key.pem /output/key.pem >/dev/null ; \
+    then
 	echo "$(date) Certificate and key still up to date, doing nothing"
     else
 	echo "$(date) Certificate or key differ, updating"