diff --git a/lib/Mojo/Log.pm b/lib/Mojo/Log.pm
index 0a05c40d1d..9bf47865ef 100644
--- a/lib/Mojo/Log.pm
+++ b/lib/Mojo/Log.pm
@@ -99,7 +99,7 @@ sub _default {
   my ($s, $m, $h, $day, $month, $year) = localtime $time;
   $time = sprintf '%04d-%02d-%02d %02d:%02d:%08.5f', $year + 1900, $month + 1, $day, $h, $m,
     "$s." . ((split /\./, $time)[1] // 0);
-  return "[$time] [$$] [$level] " . join(' ', @_) . "\n";
+  return "[$time] [$$] [$level] " . join(' ', map {defined $_ ? $_ : 'undef'} @_) . "\n";
 }
 
 sub _log {
@@ -123,7 +123,7 @@ sub _message {
 sub _short {
   my ($time, $level) = (shift, shift);
   my ($magic, $short) = ("<$MAGIC{$level}>", substr($level, 0, 1));
-  return "${magic}[$$] [$short] " . join(' ', @_) . "\n";
+  return "${magic}[$$] [$short] " . join(' ', map {defined $_ ? $_ : 'undef'} @_) . "\n";
 }
 
 package Mojo::Log::_Capture;
diff --git a/t/mojo/log.t b/t/mojo/log.t
index 5b10430052..d1fed02e6a 100644
--- a/t/mojo/log.t
+++ b/t/mojo/log.t
@@ -36,12 +36,14 @@ subtest 'Logging to STDERR' => sub {
     $log->fatal('I ♥ Mojolicious');
     $log->debug('Works too');
     $log->debug(sub { return 'And this', 'too' });
+    $log->info(undef, 'works');
   }
   my $content = decode 'UTF-8', $buffer;
   like $content, qr/\[.*\] \[error\] Just works\n/,      'right error message';
   like $content, qr/\[.*\] \[fatal\] I ♥ Mojolicious\n/, 'right fatal message';
   like $content, qr/\[.*\] \[debug\] Works too\n/,       'right debug message';
   like $content, qr/\[.*\] \[debug\] And this too\n/,    'right debug message';
+  like $content, qr/\[.*\] \[info\] undef works\n/,      'right debug message';
 };
 
 subtest 'Formatting' => sub {
@@ -73,6 +75,7 @@ subtest 'Short log messages (systemd)' => sub {
   like $log->format->(time, 'error', 'Test 123'), qr/^<3>\[\d+\] \[e\] Test 123\n$/, 'right format';
   like $log->format->(time, 'fatal', 'Test 123'), qr/^<2>\[\d+\] \[f\] Test 123\n$/, 'right format';
   like $log->format->(time, 'debug', 'Test', '1', '2', '3'), qr/^<6>\[\d+\] \[d\] Test 1 2 3\n$/, 'right format';
+  like $log->format->(time, 'debug', undef, 'works'), qr/^<6>\[\d+\] \[d\] undef works\n$/, 'right format';
 };
 
 subtest 'Colorized log messages' => sub {