lib/PublicInbox/Config.pm       | 12 ++++++++++++
 lib/PublicInbox/ManifestJsGz.pm |  8 ++------

diff --git a/lib/PublicInbox/Config.pm b/lib/PublicInbox/Config.pm
index d2010f7af8f629b896be5c19030ecfc499220334..039eb445f6bbe54daadc977959e1101fae38af3c 100644
--- a/lib/PublicInbox/Config.pm
+++ b/lib/PublicInbox/Config.pm
@@ -488,4 +488,16 @@ 		undef;
 	}
 }
 
+sub json {
+	state $json;
+	$json //= do {
+		for my $mod (qw(Cpanel::JSON::XS JSON::MaybeXS JSON JSON::PP)) {
+			eval "require $mod" or next;
+			# ->ascii encodes non-ASCII to "\uXXXX"
+			$json = $mod->new->ascii(1) and last;
+		}
+		$json;
+	};
+}
+
 1;
diff --git a/lib/PublicInbox/ManifestJsGz.pm b/lib/PublicInbox/ManifestJsGz.pm
index 16d2a87c49fd5f902d94218ec54427007161eb38..ab1478afcc38507245a8b41b9ac0ddfcb747d5c9 100644
--- a/lib/PublicInbox/ManifestJsGz.pm
+++ b/lib/PublicInbox/ManifestJsGz.pm
@@ -10,17 +10,13 @@ use Digest::SHA ();
 use File::Spec ();
 use bytes (); # length
 use PublicInbox::Inbox;
+use PublicInbox::Config;
 use PublicInbox::Git;
 use IO::Compress::Gzip qw(gzip);
 use HTTP::Date qw(time2str);
 *try_cat = \&PublicInbox::Inbox::try_cat;
 
-our $json;
-for my $mod (qw(Cpanel::JSON::XS JSON::MaybeXS JSON JSON::PP)) {
-	eval "require $mod" or next;
-	# ->ascii encodes non-ASCII to "\uXXXX"
-	$json = $mod->new->ascii(1) and last;
-}
+our $json = PublicInbox::Config::json();
 
 # called by WwwListing
 sub url_regexp {