lib/PublicInbox/GitAsyncCat.pm | 3 ++-

diff --git a/lib/PublicInbox/GitAsyncCat.pm b/lib/PublicInbox/GitAsyncCat.pm
index c12c4ec2528f750043e57abf660967d34e49e147..b32c2fd3cab4b6c665df483378b01f42952102c6 100644
--- a/lib/PublicInbox/GitAsyncCat.pm
+++ b/lib/PublicInbox/GitAsyncCat.pm
@@ -51,7 +51,8 @@ 	my $git = $ibx->{git} // $ibx->git;
 	# {topdir} means ExtSearch (likely [extindex "all"]) with potentially
 	# 100K alternates.  git(1) has a proposed patch for 100K alternates:
 	# <https://lore.kernel.org/git/20210624005806.12079-1-e@80x24.org/>
-	if (!defined($ibx->{topdir}) && ($GCF2C //= eval {
+	if (!defined($ibx->{topdir}) && !defined($git->{-tmp}) &&
+		($GCF2C //= eval {
 		require PublicInbox::Gcf2Client;
 		PublicInbox::Gcf2Client::new();
 	} // 0)) { # 0: do not retry if libgit2 or Inline::C are missing