diff --git a/modules/update/update.compare.inc b/modules/update/update.compare.inc
index 764c42cba0eebfe840710a5a1984c2e28ca9a730..996855aa746b10b78c2ef06df770861308b9160d 100644
--- a/modules/update/update.compare.inc
+++ b/modules/update/update.compare.inc
@@ -180,12 +180,7 @@ function update_get_project_name($file) {
   if (isset($file->info['project'])) {
     $project_name = $file->info['project'];
   }
-  elseif (isset($file->info['package']) && (strpos($file->info['package'], 'Core') !== FALSE)) {
-    $project_name = 'drupal';
-  }
-  elseif (in_array($file->name, array('garland', 'minnelli', 'stark'))) {
-    // Unfortunately, there's no way to tell if a theme is part of core,
-    // so we must hard-code a list here.
+  elseif (isset($file->info['package']) && (strpos($file->info['package'], 'Core') === 0)) {
     $project_name = 'drupal';
   }
   return $project_name;
diff --git a/themes/garland/garland.info b/themes/garland/garland.info
index 96089d6dd7fccd2cfc1af1c01875af51ebdd0af9..4c95977713434c38f7249eb0d456a9f418d7bf23 100644
--- a/themes/garland/garland.info
+++ b/themes/garland/garland.info
@@ -1,6 +1,7 @@
 ; $Id$
 name = Garland
 description = Tableless, recolorable, multi-column, fluid width theme.
+package = Core
 version = VERSION
 core = 7.x
 engine = phptemplate
diff --git a/themes/garland/minnelli/minnelli.info b/themes/garland/minnelli/minnelli.info
index f10c04dac0340affb7476cf1ac36f92481b3eb65..e5c88fe72fb0998f54a8deeadfdeb3c33fd5e013 100644
--- a/themes/garland/minnelli/minnelli.info
+++ b/themes/garland/minnelli/minnelli.info
@@ -1,6 +1,7 @@
 ; $Id$
 name = Minnelli
 description = Tableless, recolorable, multi-column, fixed width theme.
+package = Core
 version = VERSION
 core = 7.x
 base theme = garland
diff --git a/themes/seven/seven.info b/themes/seven/seven.info
index 6b3e9458a05f7f50780312c2840d76a25ec37feb..cce1a5e78f5e870cab6ff161e713079b9312ed0a 100644
--- a/themes/seven/seven.info
+++ b/themes/seven/seven.info
@@ -1,8 +1,9 @@
 ; $Id$
 name = Seven
 description = A simple one-column, tableless, fluid width administration theme.
-core = 7.x
+package = Core
 version = VERSION
+core = 7.x
 engine = phptemplate
 stylesheets[screen][] = reset.css
 stylesheets[screen][] = style.css
diff --git a/themes/stark/stark.info b/themes/stark/stark.info
index cf2df92ee79d6357f3f5877b4b35b27e06a70a1e..c3955fd4f65e7c90e84392873b277fd1408375d1 100644
--- a/themes/stark/stark.info
+++ b/themes/stark/stark.info
@@ -1,7 +1,7 @@
 ; $Id$
-
 name = Stark
 description = This theme demonstrates Drupal's default HTML markup and CSS styles. To learn how to build your own theme and override Drupal's default code, you should start reading the <a href="http://drupal.org/theme-guide">Theming Guide</a>.
+package = Core
 version = VERSION
 core = 7.x
 engine = phptemplate