diff --git a/Plang b/Plang
index 1d68bfb4..56528a5f 160000
--- a/Plang
+++ b/Plang
@@ -1 +1 @@
-Subproject commit 1d68bfb4b5382cb67a8733f879aeec9d860f2e05
+Subproject commit 56528a5f36e2a60d773f52e73554504cf51b70ce
diff --git a/Plugins/Plang.pm b/Plugins/Plang.pm
index 81867ba2..0eb42f67 100644
--- a/Plugins/Plang.pm
+++ b/Plugins/Plang.pm
@@ -30,6 +30,7 @@ sub initialize {
     require "$path/Grammar.pm";
     require "$path/Parser.pm";
     require "$path/Lexer.pm";
+    require "$path/Types.pm";
 
     # regset plang.debug 0-10 -- Plugin must be reloaded for this value to take effect.
     my $debug = $self->{pbot}->{registry}->get_value('plang', 'debug') // 0;
@@ -40,29 +41,46 @@ sub initialize {
     # register some PBot-specific built-in functions
     $self->{plang}->add_builtin_function('factset',
         # parameters are [['param1 name', default arg], ['param2 name', default arg], ...]
-        [['String', 'channel', undef], ['String', 'keyword', undef], ['String', 'text', undef]],
-        'String',  # return type
+        [
+            [['TYPE', 'String'], 'channel', undef],
+            [['TYPE', 'String'], 'keyword', undef],
+            [['TYPE', 'String'], 'text', undef]
+        ],
+        ['TYPE', 'String'],  # return type
         sub { $self->plang_builtin_factset(@_) });
 
     $self->{plang}->add_builtin_function('factget',
-        [['String', 'channel', undef], ['String', 'keyword', undef], ['String', 'meta', ['STRING', 'action']]],
-        'String',
+        [
+            [['TYPE', 'String'], 'channel', undef],
+            [['TYPE', 'String'], 'keyword', undef],
+            [['TYPE', 'String'], 'meta', [['TYPE', 'String'], 'action']]
+        ],
+        ['TYPE', 'String'],
         sub { $self->plang_builtin_factget(@_) });
 
     $self->{plang}->add_builtin_function('factappend',
-        [['String', 'channel', undef], ['String', 'keyword', undef], ['String', 'text', undef]],
-        'String',
+        [
+            [['TYPE', 'String'], 'channel', undef],
+            [['TYPE', 'String'], 'keyword', undef],
+            [['TYPE', 'String'], 'text', undef]
+        ],
+        ['TYPE', 'String'],
         sub { $self->plang_builtin_factappend(@_) });
 
     $self->{plang}->add_builtin_function('userget',
-        [['String', 'name', undef]],
-        'Map',
+        [
+            [['TYPE', 'String'], 'name', undef]
+        ],
+        ['TYPELIST', [['TYPE', 'Map'], ['TYPE', 'Null']]],
         sub { $self->plang_builtin_userget(@_) });
 
     # override the built-in `print` function to send to our output buffer instead
     $self->{plang}->add_builtin_function('print',
-        [['Any', 'expr', undef], ['String', 'end', ['STRING', "\n"]]],
-        'Null',
+        [
+            [['TYPE', 'Any'], 'expr', undef],
+            [['TYPE', 'String'], 'end', [['TYPE', 'String'], "\n"]]
+        ],
+        ['TYPE', 'Null'],
         sub { $self->plang_builtin_print(@_) });
 
     # register the `plang` command
@@ -130,7 +148,7 @@ sub plang_builtin_print {
     my ($self, $plang, $context, $name, $arguments) = @_;
     my ($expr, $end) = ($plang->output_value($arguments->[0]), $arguments->[1]->[1]);
     $self->{output} .= "$expr$end";
-    return ['NULL', undef];
+    return [['TYPE', 'Null'], undef];
 }
 
 # our custom PBot built-in functions for Plang
@@ -144,50 +162,46 @@ sub plang_builtin_factget {
     my ($self, $plang, $context, $name, $arguments) = @_;
     my ($channel, $keyword, $meta) = ($arguments->[0]->[1], $arguments->[1]->[1], $arguments->[2]->[1]);
     my $result = $self->{pbot}->{factoids}->get_meta($channel, $keyword, $meta);
-    return ['STRING', $result];
+    return [['TYPE', 'String'], $result];
 }
 
 sub plang_builtin_factset {
     my ($self, $plang, $context, $name, $arguments) = @_;
     my ($channel, $keyword, $text) = ($arguments->[0]->[1], $arguments->[1]->[1], $arguments->[2]->[1]);
-    return ['ERROR', "Factoid $channel.$keyword is locked. Cannot set."] if $self->is_locked($channel, $keyword);
+    die "Factoid $channel.$keyword is locked. Cannot set." if $self->is_locked($channel, $keyword);
     $self->{pbot}->{factoids}->add_factoid('text', $channel, 'Plang', $keyword, $text);
-    return ['STRING', $text];
+    return [['TYPE', 'String'], $text];
 }
 
 sub plang_builtin_factappend {
     my ($self, $plang, $context, $name, $arguments) = @_;
     my ($channel, $keyword, $text) = ($arguments->[0]->[1], $arguments->[1]->[1], $arguments->[2]->[1]);
-    return ['ERROR', "Factoid $channel.$keyword is locked. Cannot append."] if $self->is_locked($channel, $keyword);
+    die "Factoid $channel.$keyword is locked. Cannot append." if $self->is_locked($channel, $keyword);
     my $action = $self->{pbot}->{factoids}->get_meta($channel, $keyword, 'action');
     $action = "" if not defined $action;
     $action .= $text;
     $self->{pbot}->{factoids}->add_factoid('text', $channel, 'Plang', $keyword, $action);
-    return ['STRING', $action];
+    return [['TYPE', 'String'], $action];
 }
 
 sub plang_builtin_userget {
     my ($self, $plang, $context, $name, $arguments) = @_;
     my ($username) = ($arguments->[0], $arguments->[1]);
 
-    if ($username->[0] ne 'STRING') {
-        $plang->error($context, "`name` argument must be a String (got " . $plang->pretty_type($username) . ")");
-    }
-
     my $user = $self->{pbot}->{users}->{users}->get_data($username->[1]);
 
     if (not defined $user) {
-        return ['NULL', undef];
+        return [['TYPE', 'Null'], undef];
     }
 
     my $hash = { %$user };
     $hash->{password} = '<private>';
 
     while (my ($key, $value) = each %$hash) {
-        $hash->{$key} = ['STRING', $value];
+        $hash->{$key} = [['TYPE', 'String'], $value];
     }
 
-    return ['MAP', $hash];
+    return [['TYPE', 'Map'], $hash];
 }
 
 1;