diff --git a/roundcubemail/Dockerfile b/roundcubemail/Dockerfile
index 43daf48..5b54263 100644
--- a/roundcubemail/Dockerfile
+++ b/roundcubemail/Dockerfile
@@ -25,7 +25,8 @@ RUN set -ex; \
 	mkdir -p /etc/ssl/certs; \
 	curl -fLSko /etc/ssl/certs/cacert.pem https://curl.se/ca/cacert.pem
 
-ENV CURL_CA_BUNDLE=/etc/ssl/certs/cacert.pem
+ENV CURL_CA_BUNDLE=/etc/ssl/certs/cacert.pem \
+	SSL_CERT_FILE=/etc/ssl/certs/cacert.pem
 
 # install composer
 RUN set -ex; \