lib/PublicInbox/GitHTTPBackend.pm | 6 +++++-

diff --git a/lib/PublicInbox/GitHTTPBackend.pm b/lib/PublicInbox/GitHTTPBackend.pm
index 61a1356048bfc735ed96cf9714f8257378042ff3..3aae54548dc990fef9e93e0e751a7fc7e782664a 100644
--- a/lib/PublicInbox/GitHTTPBackend.pm
+++ b/lib/PublicInbox/GitHTTPBackend.pm
@@ -155,7 +155,11 @@ 		$ctx{env} = +{ %{$ctx->{env}} };
 		delete $ctx->{env}->{'qspawn.wcb'};
 		$ctx->{env}->{'plack.skip-deflater'} = 1; # prevent 2x gzip
 		my $res = $ctx->{www}->coderepo->srv(\%ctx);
-		$res->(delete $ctx{env}->{'qspawn.wcb'}) if ref($res) eq 'CODE';
+		if (ref($res) eq 'CODE') {
+			$res->(delete $ctx{env}->{'qspawn.wcb'});
+		} else { # ref($res) eq 'ARRAY'
+			$ctx->{env}->{'qspawn.wcb'} = $ctx{env}->{'qspawn.wcb'};
+		}
 		$res; # non ARRAY ref for ->psgi_return_init_cb
 	} else {
 		[ $code, \@h ]