lib/PublicInbox/LeiExportKw.pm        | 2 +-
 lib/PublicInbox/LeiImport.pm          | 4 ++--
 lib/PublicInbox/LeiLsMailSource.pm    | 4 ++--
 lib/PublicInbox/LeiRefreshMailSync.pm | 2 +-

diff --git a/lib/PublicInbox/LeiExportKw.pm b/lib/PublicInbox/LeiExportKw.pm
index cea9beeb569424315aaf57ff5536d0696148408a..0b65c27626336ac679c2bab3ce815240d1e73986 100644
--- a/lib/PublicInbox/LeiExportKw.pm
+++ b/lib/PublicInbox/LeiExportKw.pm
@@ -131,7 +131,7 @@ 	my $lms = $lei->lms or return ();
 	my $match_cb = $lei->complete_url_prepare(\@argv);
 	# filter-out read-only sources:
 	my @k = grep(!m!(?://;AUTH=ANONYMOUS\@|\A(?:nntps?|s?news)://)!,
-			$lms->folders($argv[-1], 1));
+			$lms->folders($argv[-1] // undef, 1));
 	my @m = map { $match_cb->($_) } @k;
 	@m ? @m : @k;
 }
diff --git a/lib/PublicInbox/LeiImport.pm b/lib/PublicInbox/LeiImport.pm
index 397292d4c7878e4192aa5766a2fa7188166352bd..69d63ab6b39756f96a89deb49422fb9eaadcb444 100644
--- a/lib/PublicInbox/LeiImport.pm
+++ b/lib/PublicInbox/LeiImport.pm
@@ -122,11 +122,11 @@
 sub _complete_import {
 	my ($lei, @argv) = @_;
 	my ($re, $cur, $match_cb) = $lei->complete_url_prepare(\@argv);
-	my @k = $lei->url_folder_cache->keys($argv[-1], 1);
+	my @k = $lei->url_folder_cache->keys($argv[-1] // undef, 1);
 	my @m = map { $match_cb->($_) } @k;
 	my %f = map { $_ => 1 } (@m ? @m : @k);
 	if (my $lms = $lei->lms) {
-		@k = $lms->folders($argv[-1], 1);
+		@k = $lms->folders($argv[-1] // undef, 1);
 		@m = map { $match_cb->($_) } @k;
 		if (@m) { @f{@m} = @m } else { @f{@k} = @k }
 	}
diff --git a/lib/PublicInbox/LeiLsMailSource.pm b/lib/PublicInbox/LeiLsMailSource.pm
index 1db15d5742b557966f41cce9ede496b49ced4380..7c3c0cda18d61365bb982990ac7f83ec3ec3516f 100644
--- a/lib/PublicInbox/LeiLsMailSource.pm
+++ b/lib/PublicInbox/LeiLsMailSource.pm
@@ -107,11 +107,11 @@
 sub _complete_ls_mail_source {
 	my ($lei, @argv) = @_;
 	my $match_cb = $lei->complete_url_prepare(\@argv);
-	my @k = $lei->url_folder_cache->keys($argv[-1], 1);
+	my @k = $lei->url_folder_cache->keys($argv[-1] // undef, 1);
 	my @m = map { $match_cb->($_) } @k;
 	my %f = map { $_ => 1 } (@m ? @m : @k);
 	if (my $lms = $lei->lms) {
-		@k = $lms->folders($argv[-1], 1);
+		@k = $lms->folders($argv[-1] // undef, 1);
 		@m = map { $match_cb->($_) } grep(m!\A[a-z]+://!, @k);
 		if (@m) { @f{@m} = @m } else { @f{@k} = @k }
 	}
diff --git a/lib/PublicInbox/LeiRefreshMailSync.pm b/lib/PublicInbox/LeiRefreshMailSync.pm
index eb842843b51dece6664aad113e26efa4d22b4096..0cb9f3dccd48ae934937541453692fd492c91e4a 100644
--- a/lib/PublicInbox/LeiRefreshMailSync.pm
+++ b/lib/PublicInbox/LeiRefreshMailSync.pm
@@ -101,7 +101,7 @@ sub _complete_refresh_mail_sync {
 	my ($lei, @argv) = @_;
 	my $lms = $lei->lms or return ();
 	my $match_cb = $lei->complete_url_prepare(\@argv);
-	my @k = $lms->folders($argv[-1], 1);
+	my @k = $lms->folders($argv[-1] // undef, 1);
 	my @m = map { $match_cb->($_) } @k;
 	@m ? @m : @k
 }