diff --git a/files/Dockerfile b/files/Dockerfile
index 814d7c2..e8a350d 100644
--- a/files/Dockerfile
+++ b/files/Dockerfile
@@ -16,7 +16,7 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
   && mkdir -p /vmail && chown vmail:vmail /vmail \
   && mkdir -p /ssl && chmod 700 /ssl \
   && cp /etc/ssl/certs/ssl-cert-snakeoil.pem /ssl/cert.pem \
-  && cp /etc/ssl/private/ssl-cert-snakeoil.pem /ssl/key.pem \
+  && cp /etc/ssl/private/ssl-cert-snakeoil.key /ssl/key.pem \
   && mkdir -p /etc/dovecot/sieve/before /etc/dovecot/sieve/after
 
 ADD 10-mail.conf \