diff --git a/Dockerfile b/Dockerfile
index d4fe87e..809c056 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -23,7 +23,7 @@ ENV ROUNDCUBEMAIL_VERSION=1.3.10
 
 # Download package and extract to web volume
 RUN set -ex; \
-	fetchDeps="gnupg dirmngr"; \
+	fetchDeps="gnupg dirmngr ssl-cert"; \
 	apt-get -qq update; \
 	apt-get install -y --no-install-recommends $fetchDeps; \
 	curl -o roundcubemail.tar.gz -fSL https://github.com/roundcube/roundcubemail/releases/download/${ROUNDCUBEMAIL_VERSION}/roundcubemail-${ROUNDCUBEMAIL_VERSION}-complete.tar.gz; \
@@ -56,12 +56,9 @@ VOLUME /tmp/roundcube-temp
 
 # launch and configure Unit
 RUN \
-# generate self-signed certificate
+# generate self-signed certificate bundle
 	mkdir -p /ssl; \
-	openssl genpkey -algorithm RSA -out /ssl/key.pem -pkeyopt rsa_keygen_bits:4096; \
-	chmod 600 /ssl/key.pem; \
-	openssl rsa -pubout -in /ssl/key.pem -out /ssl/cert.pem; \
-	cat /ssl/cert.pem /ssl/key.pem > /ssl/bundle.pem; \
+	cat /etc/ssl/certs/ssl-cert-snakeoil.pem /etc/ssl/private/ssl-cert-snakeoil.key > /ssl/bundle.pem; \
 	chmod 600 /ssl/bundle.pem; \
 # create mock index files for configuring unit
 	[ -d /var/www/html/public_html ] || { \