diff --git a/Dockerfile b/Dockerfile
index cb08c98..0c93b7a 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -22,8 +22,7 @@ RUN apk add --no-cache \
     openssl \
     spamassassin-client \
     libstdc++ \
-    libmilter \
-    db
+    libmilter
 
 RUN addgroup -g 2222 access
 RUN addgroup postfix access
diff --git a/rootfs/etc/confd/templates/main.cf.tmpl b/rootfs/etc/confd/templates/main.cf.tmpl
index a375894..1088f32 100644
--- a/rootfs/etc/confd/templates/main.cf.tmpl
+++ b/rootfs/etc/confd/templates/main.cf.tmpl
@@ -47,8 +47,8 @@ smtpd_tls_wrappermode = no
 lmtp_tls_mandatory_ciphers = $smtpd_tls_mandatory_ciphers
 lmtp_tls_ciphers = $smtpd_tls_ciphers
 
-smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
-smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache
+smtpd_tls_session_cache_database = lmdb:${data_directory}/smtpd_scache
+smtp_tls_session_cache_database = lmdb:${data_directory}/smtp_scache
 
 smtpd_sasl_type = dovecot
 smtpd_sasl_path = inet:{{getenv "DOVECOT_HOST"}}:{{getenv "DOVECOT_AUTH_PORT"}}