lib/PublicInbox/InboxIdle.pm | 5 ++++-

diff --git a/lib/PublicInbox/InboxIdle.pm b/lib/PublicInbox/InboxIdle.pm
index c19b8d186cdcdfd88f13d1f38d11c2d835b5d850..d60d4f239c381e2d8fd07d0247a016da78e30269 100644
--- a/lib/PublicInbox/InboxIdle.pm
+++ b/lib/PublicInbox/InboxIdle.pm
@@ -58,7 +58,10 @@ 		$inot = $ino_cls->new or die "E: $ino_cls->new: $!";
 		my $sock = gensym;
 		tie *$sock, 'PublicInbox::In2Tie', $inot;
 		$inot->blocking(0);
-		$inot->on_overflow(undef); # broadcasts everything on overflow
+		if ($inot->can('on_overflow')) {
+			 # broadcasts everything on overflow
+			$inot->on_overflow(undef);
+		}
 		$self->SUPER::new($sock, EPOLLIN | EPOLLET);
 	} else {
 		require PublicInbox::FakeInotify;