diff --git a/modoboa_installer/scripts/opendkim.py b/modoboa_installer/scripts/opendkim.py
index d6e4818..c119547 100644
--- a/modoboa_installer/scripts/opendkim.py
+++ b/modoboa_installer/scripts/opendkim.py
@@ -90,3 +90,10 @@ class Opendkim(base.Installer):
                 "",
                 'SOCKET="inet:12345@localhost"',
             ]))
+        # Make sure opendkim is started after postgresql and mysql, respectively
+        dbservice = "postgresql.service" if self.dbengine == "postgres" else "mysql.service"
+        pattern = (
+            "s/^After=(.*)$/After=$1 {}/".format(dbservice)
+        )
+        utils.exec_cmd(
+            "perl -pi -e '{}' /lib/systemd/system/opendkim.service".format(pattern))