diff --git a/lib/Net/ACME2.pm b/lib/Net/ACME2.pm
index 949907a..d8692b8 100644
--- a/lib/Net/ACME2.pm
+++ b/lib/Net/ACME2.pm
@@ -1043,7 +1043,7 @@ sub _key_thumbprint {
 sub _get_directory {
     my ($self) = @_;
 
-    return $self->{'_directory_promise'} ||= do {
+    return $self->{'_directory_cache'} ||= do {
         my $dir_path = $self->DIRECTORY_PATH();
 
         my $http = $self->{'_http'};
@@ -1190,10 +1190,6 @@ sub _die_generic {
 *create_new_account = *create_account;
 *create_new_order = *create_order;
 
-# sub DESTROY {
-#     print "ACME2 destroyed at ${^GLOBAL_PHASE}\n";
-# }
-
 1;
 
 =head1 TODO
diff --git a/lib/Net/ACME2/Curl.pm b/lib/Net/ACME2/Curl.pm
index 1d414dd..39d62fe 100644
--- a/lib/Net/ACME2/Curl.pm
+++ b/lib/Net/ACME2/Curl.pm
@@ -136,6 +136,8 @@ sub _imitate_http_tiny {
 
     my %headers;
     for my $line ( split m<\x0d?\x0a>, $head ) {
+        next if !length $line;
+
         if (defined $reason) {
             my ($name, $value) = split m<\s*:\s*>, $line, 2;
             $name =~ tr<A-Z><a-z>;
diff --git a/lib/Net/ACME2/HTTP.pm b/lib/Net/ACME2/HTTP.pm
index 7e397cf..d15629b 100644
--- a/lib/Net/ACME2/HTTP.pm
+++ b/lib/Net/ACME2/HTTP.pm
@@ -39,11 +39,7 @@ our $verify_SSL = 1;
 sub new {
     my ( $class, %opts ) = @_;
 
-    my $is_sync;
-
     $opts{'ua'} ||= do {
-        $is_sync = 1;
-
         require Net::ACME2::HTTP_Tiny;
         Net::ACME2::HTTP_Tiny->new( verify_SSL => $verify_SSL );
     };
@@ -53,7 +49,6 @@ sub new {
         _acme_key => $opts{'key'},
         _key_id => $opts{'key_id'},
         _retries_left => $_MAX_RETRIES,
-        _sync_io => $is_sync,
     }, $class;
 
     return bless $self, $class;
@@ -144,8 +139,6 @@ sub _post {
         sub {
             my $jws = shift;
 
-            # local $opts_hr->{'headers'}{'Content-Type'} = 'application/jose+json';
-
             return Net::ACME2::PromiseUtil::do_then_catch(
                 sub {
                     return $self->_request_and_set_last_nonce(
@@ -170,6 +163,10 @@ sub _post {
 
                     my $resp;
 
+                    # NB: We mutate $self->{'_retries_left'} rather than
+                    # using local() because this code may run inside a
+                    # promise chain where local's dynamic scope doesn't
+                    # extend across async callbacks.
                     if ( eval { $err->get('acme')->type() =~ m<:badNonce\z> } ) {
                         if (!$self->{'_retries_left'}) {
                             warn( "$url: Received “badNonce” error, and no retries left!\n" );