diff --git a/lib/Lacuna/DB/Result/Building/Capitol.pm b/lib/Lacuna/DB/Result/Building/Capitol.pm
index 3d98bb41..4a4ada4f 100644
--- a/lib/Lacuna/DB/Result/Building/Capitol.pm
+++ b/lib/Lacuna/DB/Result/Building/Capitol.pm
@@ -52,6 +52,14 @@ before 'can_demolish' => sub {
     }
 };
 
+before 'can_downgrade' => sub {
+    my $self = shift;
+    my $stockpile = $self->body->get_building_of_class('Lacuna::DB::Result::Building::Stockpile');
+    if (defined $stockpile) {
+        confess [1013, 'You have to demolish your Stockpile before you can downgrade your Capitol.'];
+    }
+};
+
 before can_build => sub {
     my $self = shift;
     my @ids = $self->body->empire->planets->get_column('id')->all;