diff --git a/lib/MusicBrainz/Server/Form/Field/Comment.pm b/lib/MusicBrainz/Server/Form/Field/Comment.pm
index 4632ac16391..721f00d415d 100644
--- a/lib/MusicBrainz/Server/Form/Field/Comment.pm
+++ b/lib/MusicBrainz/Server/Form/Field/Comment.pm
@@ -6,6 +6,9 @@ extends 'HTML::FormHandler::Field::Text';
 
 has '+maxlength' => ( default => 255 );
 has '+not_nullable' => ( default => 1 );
+has '+validate_when_empty' => (
+    default => 1
+);
 
 apply ([
     {
diff --git a/t/lib/t/MusicBrainz/Server/Controller/Artist/Create.pm b/t/lib/t/MusicBrainz/Server/Controller/Artist/Create.pm
index 0aeca3bebb5..5d49bd463d7 100644
--- a/t/lib/t/MusicBrainz/Server/Controller/Artist/Create.pm
+++ b/t/lib/t/MusicBrainz/Server/Controller/Artist/Create.pm
@@ -275,6 +275,41 @@ test 'MBS-10976: Private use characters U+E000..U+F8FF are allowed' => sub {
     );
 };
 
+test 'MBS-12351: Space-only disambiguations are trimmed properly' => sub {
+    my $test = shift;
+    my $mech = $test->mech;
+
+    prepare_test($test);
+
+    $mech->get_ok('/artist/create');
+
+    my @edits = capture_edits {
+        $mech->submit_form_ok({
+            with_fields => {
+                'edit-artist.name' => 'Testy',
+                'edit-artist.sort_name' => 'Testy',
+                'edit-artist.comment' => '   ',
+            },
+        },
+        'The form returned a 2xx response code')
+    } $test->c;
+
+    ok(
+        $mech->uri =~ $artist_page_regexp,
+        'The user is redirected to the artist page after entering the edit',
+    );
+
+    is(@edits, 1, 'The edit was entered');
+
+    my $edit = shift(@edits);
+
+    is(
+        $edit->data->{comment},
+        '',
+        'The submitted comment is empty',
+    );
+};
+
 sub prepare_test {
     my $test = shift;
 
diff --git a/t/lib/t/MusicBrainz/Server/Controller/Artist/EditRelationships.pm b/t/lib/t/MusicBrainz/Server/Controller/Artist/EditRelationships.pm
index 477d6fadd79..62bc9e893ce 100644
--- a/t/lib/t/MusicBrainz/Server/Controller/Artist/EditRelationships.pm
+++ b/t/lib/t/MusicBrainz/Server/Controller/Artist/EditRelationships.pm
@@ -35,6 +35,7 @@ test 'Test adding a relationship' => sub {
         $mech->post('/artist/745c079d-374e-4436-9448-da92dedef3ce/edit', {
             'edit-artist.name' => 'Test Artist',
             'edit-artist.sort_name' => 'Artist, Test',
+            'edit-artist.comment' => 'Yet Another Test Artist',
             'edit-artist.type_id' => '1',
             'edit-artist.gender_id' => '1',
             'edit-artist.period.ended' => '1',