diff --git a/roundcubemail/Dockerfile b/roundcubemail/Dockerfile
index 4490ab8..c8d0e11 100644
--- a/roundcubemail/Dockerfile
+++ b/roundcubemail/Dockerfile
@@ -19,6 +19,7 @@ RUN set -ex; \
 		dirmngr \
 		locales \
 		libc-l10n \
+		ca-certificates \
 	; \
 	rm -rf /var/lib/apt/lists/*; \
 	a2enmod rewrite