diff --git a/data/Dockerfiles/dovecot/imapsync_cron.pl b/data/Dockerfiles/dovecot/imapsync_cron.pl
index c441d7f9..47f9bbf7 100755
--- a/data/Dockerfiles/dovecot/imapsync_cron.pl
+++ b/data/Dockerfiles/dovecot/imapsync_cron.pl
@@ -77,7 +77,7 @@ while ($row = $sth->fetchrow_arrayref()) {
 	"--nofoldersizes",
 	"--skipsize",
 	"--buffersize 8192000",
-	"--skipheader 'X-*",
+	"--skipheader 'X-*'",
 	"--split1 3000",
 	"--split2 3000",
 	"--fastio1",