diff --git a/.travis.yml b/.travis.yml
index 289fd8b1..b02f1c6c 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -2,7 +2,7 @@ language: perl
 install:
   - sudo apt-get install vim
   - cpanm --notest Test::Differences Text::VimColor IO::Pty Test::Deep Parallel::ForkManager JSON Path::Tiny Test::SharedFork Test::LongString
-  - git fetch origin p5-corpus:origin/p5-corpus
+  - git fetch origin p5-corpus-ng:origin/p5-corpus-ng
   - vim --version
 script:
   - make test
diff --git a/build-corpus.pl b/build-corpus.pl
index 6d38c67f..545d244f 100755
--- a/build-corpus.pl
+++ b/build-corpus.pl
@@ -123,7 +123,7 @@ sub create_tree {
 
 my $json = JSON->new->utf8->canonical;
 
-my $iter = get_blob_iterator('origin/p5-corpus', 'corpus');
+my $iter = get_blob_iterator('origin/p5-corpus-ng', 'corpus');
 my $tree = {};
 
 while(my ( $filename, $contents ) = $iter->()) {
@@ -133,26 +133,26 @@ sub create_tree {
     print { $source } $contents;
     close $source;
 
-    my $html  = $color->color_file($source->filename);
+    my $marked  = $color->markup_file($source->filename);
     my @folds = $fold->_get_folds($source->filename);
 
-    my $html_filename = $filename;
-    $html_filename    =~ s{\Acorpus/}{};
-    $html_filename   .= '.html';
+    my $marked_filename = $filename;
+    $marked_filename    =~ s{\Acorpus/}{};
+    $marked_filename   .= '.json';
 
     my $folds_filename = $filename;
     $folds_filename    =~ s{\Acorpus/}{};
     $folds_filename   .= '-folds.json';
 
-    insert_into_tree($tree, $html_filename, $html);
+    insert_into_tree($tree, $marked_filename, $json->encode($marked));
     insert_into_tree($tree, $folds_filename, $json->encode(\@folds));
 }
 
 $tree = create_tree($tree);
 
-my $corpus_tree = find_git_object('origin/p5-corpus', 'corpus');
+my $corpus_tree = find_git_object('origin/p5-corpus-ng', 'corpus');
 
-$tree = two_way_pipe('git', 'mktree', "040000 tree $tree\tcorpus_html\n040000 tree $corpus_tree\tcorpus\n");
+$tree = two_way_pipe('git', 'mktree', "040000 tree $tree\tcorpus_marked\n040000 tree $corpus_tree\tcorpus\n");
 chomp $tree;
 
 open my $pipe, '-|', 'git', 'commit-tree', '-m', 'Update Perl 5 corpus', $tree;
@@ -160,5 +160,5 @@ sub create_tree {
 close $pipe;
 chomp $commit;
 
-system 'git', 'update-ref', 'refs/heads/p5-corpus', $commit;
-system 'git', 'push', 'origin', '--force', 'p5-corpus:p5-corpus';
+system 'git', 'update-ref', 'refs/heads/p5-corpus-ng', $commit;
+system 'git', 'push', 'origin', '--force', 'p5-corpus-ng:p5-corpus-ng';
diff --git a/t/06_corpus.t b/t/06_corpus.t
index 5b9e831f..b02663cf 100644
--- a/t/06_corpus.t
+++ b/t/06_corpus.t
@@ -10,12 +10,253 @@ use Local::VimFolds;
 use Local::Utils;
 
 use File::Temp;
+use JSON qw(decode_json);
+use List::Util qw(min max);
 use Parallel::ForkManager;
 use Path::Tiny;
 use Test::Differences;
 use Test::More;
 use Test::SharedFork;
-use Test::LongString;   # for is_string()
+
+# XXX these values are currently taken from peaksea.vim
+#     what about terminal attributes like bold?
+my %fg_color_map = (
+    Identifier => 219,
+    Statement  => 153,
+    Type       => 153,
+    Constant   => 110,
+    Comment    => 186,
+    Number     => 179,
+    PreProc    => 84,
+    Special    => 179,
+    Todo       => 88,
+
+    '' => 253,
+);
+
+my %bg_color_map = (
+    '' => '',
+);
+
+$fg_color_map{'String'}      = $fg_color_map{'Constant'};
+$fg_color_map{'Float'}       = $fg_color_map{'Number'};
+$fg_color_map{'Conditional'} = $fg_color_map{'Statement'};
+$fg_color_map{'Operator'}    = $fg_color_map{'Statement'};
+$fg_color_map{'Keyword'}     = $fg_color_map{'Statement'};
+$fg_color_map{'Function'}    = $fg_color_map{'Statement'};
+$fg_color_map{'Label'}       = $fg_color_map{'Statement'};
+$fg_color_map{'Repeat'}      = $fg_color_map{'Statement'};
+
+my $GRAY =  "\e[38;5;243m";
+my $RESET = "\e[0m";
+
+sub lines_from_marked {
+    my ($marked) = @_;
+    my @lines = ();
+    my $current_line = [];
+
+    foreach my $elem (@$marked) {
+        my ( $group, $text ) = @$elem;
+
+        if($text =~ /\n/) {
+            while(my ( $prefix, $postfix ) = $text =~ /^(.*?)\n(.*)$/s) {
+                if($prefix ne '') {
+                    push @$current_line, [ $group, $prefix ];
+                }
+                push @lines, $current_line;
+                $current_line = [];
+                $text = $postfix;
+            }
+
+            if($text ne '') {
+                push @$current_line, [ $group, $text ];
+            }
+        } else {
+            push @$current_line, $elem;
+        }
+    }
+    if(@$current_line) {
+        push @lines, $current_line;
+    }
+
+    return @lines;
+}
+
+# XXX not Unicode-aware! naïve implementation for now (sanity check the underlying text)
+sub split_glyphs {
+    my ($s) = @_;
+    return $s =~ /(.)/g;
+}
+
+sub build_color_map {
+    my ($marked) = @_;
+    my @map;
+
+    for my $line (lines_from_marked($marked)) {
+        my $map_line = [];
+        push @map, $map_line;
+
+        for my $grouping (@$line) {
+            my ( $group, $text ) = @$grouping;
+
+            for my $glyph (split_glyphs($text)) {
+                push @$map_line, $group;
+            }
+        }
+    }
+
+    return \@map;
+}
+
+sub build_glyph_map {
+    my ($marked) = @_;
+    my @map;
+
+    for my $line (lines_from_marked($marked)) {
+        my $map_line = [];
+        push @map, $map_line;
+
+        for my $grouping (@$line) {
+            my ( $group, $text ) = @$grouping;
+
+            for my $glyph (split_glyphs($text)) {
+                push @$map_line, $glyph;
+            }
+        }
+    }
+
+    return \@map;
+}
+
+sub is_visible {
+    my ($glyph) = @_;
+    return $glyph !~ /\pZ/; # XXX is this good enough?
+}
+
+sub find_differently_colored_lines {
+    my ($a_lines, $b_lines) = @_;
+    my @differences;
+
+    my $glyph_map  = build_glyph_map($a_lines);
+    my $before_map = build_color_map($a_lines);
+    my $after_map  = build_color_map($b_lines);
+
+    # XXX assert that dimensions for maps match
+
+    for my $lindex (0..$#$before_map) {
+        my $line_no = $lindex + 1;
+
+        my $before_line = $before_map->[$lindex];
+        my $after_line  = $after_map->[$lindex];
+
+        for my $cindex (0..$#$before_line) {
+            my $column_no = $cindex + 1;
+
+            my $glyph        = $glyph_map->[$lindex][$cindex];
+            my $before_group = $before_line->[$cindex];
+            my $after_group  = $after_line->[$cindex];
+
+            my $before_fg_color = $fg_color_map{$before_group} or die "no fg color $before_group";
+            my $after_fg_color  = $fg_color_map{$after_group}  or die "no fg color $after_group";
+            my $before_bg_color = $bg_color_map{$before_group} || $bg_color_map{''};
+            my $after_bg_color  = $bg_color_map{$after_group}  || $bg_color_map{''};
+
+            if($before_bg_color ne $after_bg_color) {
+                push @differences, [ $lindex, $cindex ];
+            }
+            if(is_visible($glyph) && $before_fg_color ne $after_fg_color) {
+                push @differences, [ $lindex, $cindex ];
+            }
+        }
+    }
+
+    return \@differences;
+}
+
+sub get_color_code {
+    my ($group) = @_;
+
+    my $fg_color_code = $fg_color_map{$group};
+    if($fg_color_code ne '') {
+        $fg_color_code = "\e[38;5;${fg_color_code}m";
+    }
+
+    my $bg_color_code = $bg_color_map{$group} || '';
+    if($bg_color_code ne '') {
+        $bg_color_code = "\e[38;5;${bg_color_code}m";
+    }
+
+    return $fg_color_code . $bg_color_code;
+}
+
+sub color_line {
+    my ($line) = @_;
+    my @pieces;
+    for my $chunk (@$line) {
+        my ( $group, $text ) = @$chunk;
+        my $color_code = get_color_code($group);
+        push @pieces, $color_code, $text, $RESET;
+    }
+    return join('', @pieces);
+}
+
+sub extract_text {
+    my ($line) = @_;
+    return join('', map { $_->[1] } @$line);
+}
+
+# XXX only print the first N differences?
+#     visually indicate the differing columns (via underline, reverse video, etc)?
+#     handle terminals too narrow to show results
+sub diag_differences {
+    my ($before_lines, $after_lines, $diffs) = @_;
+    my $num_context = 3;
+    my @print_me = map { '' } 0..$#$before_lines;
+
+    for my $diff (@$diffs) {
+        my ( $line_no, undef ) = @$diff;
+        for my $line (max(0, $line_no - 3)..min($#$before_lines, $line_no + 3)) {
+            $print_me[$line] = 'context';
+        }
+    }
+
+    for my $diff (@$diffs) {
+        my ( $line_no, undef ) = @$diff;
+        $print_me[$line_no] = 'diff';
+    }
+
+    my $max_line_length = 0;
+
+    for my $lindex (0..$#print_me) {
+        if($print_me[$lindex]) {
+            $max_line_length = max($max_line_length, length(extract_text($before_lines->[$lindex])));
+        }
+    }
+
+    for my $lindex (0..$#print_me) {
+        my $line_no = $lindex + 1;
+        my $padding;
+
+        if($print_me[$lindex]) {
+            $padding = ' ' x ($max_line_length - length(extract_text($before_lines->[$lindex])));
+        }
+
+        if($print_me[$lindex] eq 'context') {
+            diag $GRAY, sprintf('%4d', $line_no),
+                ' ',
+                extract_text($before_lines->[$lindex]) . $padding,
+                ' | ',
+                extract_text($after_lines->[$lindex]),
+                $RESET;
+        } elsif($print_me[$lindex] eq 'diff') {
+            diag sprintf('%4d', $line_no),
+                ' ',
+                color_line($before_lines->[$lindex]) . $padding,
+                ' | ',
+                color_line($after_lines->[$lindex]);
+        }
+    }
+}
 
 my $color = Local::VimColor->new(
     language => 'perl',
@@ -31,40 +272,46 @@ my $fold = Local::VimFolds->new(
 );
 
 my $pm         = Parallel::ForkManager->new(16);
-my $iter       = get_blob_iterator('origin/p5-corpus', 'corpus');
-my $is_passing = 1;
+my $iter       = get_blob_iterator('origin/p5-corpus-ng', 'corpus');
 
 $pm->run_on_finish(sub {
-    my ( undef, $status ) = @_;
+    my ( undef, $status, undef, undef, undef, $data ) = @_;
+
+    my ( $filename, $expected_marked, $got_marked, $expected_folds, $got_folds ) = @$data;
 
-    $is_passing &&= ($status == 0);
+    # XXX calculate differences in child?
+    my $differences = find_differently_colored_lines($expected_marked, $got_marked);
+    ok(!@$differences, "colors for file '$filename' match");
+    if(@$differences) {
+        diag_differences([ lines_from_marked($expected_marked) ],
+            [ lines_from_marked($got_marked) ], $differences);
+    }
+    eq_or_diff($got_folds, $expected_folds, "folds for file '$filename' match");
 });
 
 while(my ( $filename, $content ) = $iter->()) {
     next unless $filename =~ /(?:pm|pl)\z/;
     next if $pm->start;
 
-    my $expected_html  = get_html_output_for($filename);
-    my @expected_folds = get_folds_for($filename);
+    my $marks_filename = ($filename =~ s{\Acorpus}{corpus_marked}r) . '.json';
+    my $expected_marked = decode_json(get_corpus_contents($marks_filename));
+    my @expected_folds  = get_folds_for($filename);
 
     my $source = File::Temp->new;
     print { $source } $content;
     close $source;
 
-    my $got_html  = $color->color_file($source->filename);
+    my $got_marked  = $color->markup_file($source->filename);
     my @got_folds = $fold->_get_folds($source->filename);
 
-    is_string($got_html, $expected_html, "colors for file '$filename' match");
-    eq_or_diff(\@got_folds, \@expected_folds, "folds for file '$filename' match");
-
-    $pm->finish(Test::More->builder->is_passing ? 0 : 1);
+    $pm->finish(0, [ $filename, $expected_marked, $got_marked, \@expected_folds, \@got_folds ]);
 }
 
 $pm->wait_all_children;
 
-unless($is_passing) {
+unless(Test::More->builder->is_passing) {
     diag <<'END_DIAG';
-The corpus test failed!  This means that among the files stored under corpus/ in the p5-corpus
+The corpus test failed!  This means that among the files stored under corpus/ in the p5-corpus-ng
 branch, the syntax highlighting and/or the folding has changed for one or more files.  You need
 to let a vim-perl maintainer know about this!
 
diff --git a/tools/Local/Utils.pm b/tools/Local/Utils.pm
index fa7f2303..41de68ad 100644
--- a/tools/Local/Utils.pm
+++ b/tools/Local/Utils.pm
@@ -89,7 +89,7 @@ sub get_blob_iterator {
 sub get_corpus_contents {
     my ( $filename ) = @_;
 
-    open my $pipe, '-|', 'git', 'show', 'origin/p5-corpus:' . $filename;
+    open my $pipe, '-|', 'git', 'show', 'origin/p5-corpus-ng:' . $filename;
     my $content = do {
         local $/;
         <$pipe>
@@ -98,19 +98,10 @@ sub get_corpus_contents {
     return $content;
 }
 
-sub get_html_output_for {
-    my ( $filename ) = @_;
-
-    $filename  =~ s{\Acorpus/}{corpus_html/};
-    $filename .= '.html';
-
-    return get_corpus_contents($filename);
-}
-
 sub get_folds_for {
     my ( $filename ) = @_;
 
-    $filename  =~ s{\Acorpus/}{corpus_html/};
+    $filename  =~ s{\Acorpus/}{corpus_marked/};
     $filename .= '-folds.json';
 
     my $contents = get_corpus_contents($filename);
@@ -118,6 +109,6 @@ sub get_folds_for {
     return @{ decode_json($contents) };
 }
 
-our @EXPORT = qw(get_blob_iterator get_corpus_contents get_html_output_for get_folds_for find_git_object);
+our @EXPORT = qw(get_blob_iterator get_corpus_contents get_folds_for find_git_object);
 
 1;
diff --git a/tools/Local/VimColor.pm b/tools/Local/VimColor.pm
index a7225bcb..f093e7a2 100644
--- a/tools/Local/VimColor.pm
+++ b/tools/Local/VimColor.pm
@@ -40,4 +40,10 @@ sub color_file {
     return $self->{'hilite'}->syntax_mark_file($filename)->html;
 }
 
+sub markup_file {
+    my ( $self, $filename ) = @_;
+
+    return $self->{'hilite'}->syntax_mark_file($filename)->marked;
+}
+
 1;