diff --git a/core/Dockerfile b/core/Dockerfile
index a07adcc..9579f28 100644
--- a/core/Dockerfile
+++ b/core/Dockerfile
@@ -14,7 +14,7 @@ RUN apk update \
     && python3 -m pip install -U pip setuptools wheel \
         && python3 -m pip install psycopg2 \
                    gunicorn==19.9.0 \
-                   mailman==3.3.3 \
+                   mailman==3.3.4 \
                    mailman-hyperkitty==1.1.0 \
                    pymysql \
                    'sqlalchemy<1.4.0' \