diff --git a/system.admin.inc b/system.admin.inc
index 4e8e936..37db885 100644
--- a/system.admin.inc
+++ b/system.admin.inc
@@ -150,7 +150,10 @@ function system_themes_page() {
      // Ensure this theme is compatible with this version of core.
      // Require the 'content' region to make sure the main page
      // content has a common place in all themes.
-      $theme->incompatible_core = !isset($theme->info['core']) || ($theme->info['core'] != DRUPAL_CORE_COMPATIBILITY) || (!isset($theme->info['regions']['content']));
+      $theme->incompatible_core_empty = !isset($theme->info['core']);
+      $theme->incompatible_core_version = !$theme->incompatible_core_empty && $theme->info['core'] !== DRUPAL_CORE_COMPATIBILITY;
+      $theme->incompatible_core_content = isset($theme->info['regions']['content']);
+      $theme->incompatible_core = !($theme->incompatible_core_empty && $theme->incompatible_core_version && $theme->incompatible_core_content);
       $theme->incompatible_php = version_compare(phpversion(), $theme->info['php']) < 0;
     }
     $query['token'] = drupal_get_token('system-theme-operation-link');
@@ -2687,8 +2690,21 @@ function theme_system_themes_page($variables) {
       $output .= '<div class="'. join(' ', $theme->classes) .'">' . $screenshot . '<div class="theme-info"><h3>' . $theme->info['name'] . ' ' . (isset($theme->info['version']) ? $theme->info['version'] : '') . $notes . '</h3><div class="theme-description">' . $description . '</div>';
 
       // Make sure to provide feedback on compatibility.
-      if (!empty($theme->incompatible_core)) {
-        $output .= '<div class="incompatible">' . t('This version is not compatible with Drupal !core_version and should be replaced.', array('!core_version' => DRUPAL_CORE_COMPATIBILITY)) . '</div>';
+      if (!empty($theme->incompatible_core) && $theme->incompatible_core) {
+        $output .= '<div class="incompatible">';
+        if ($theme->incompatible_core_empty) {
+          $output .= t('This version is not compatible with Drupal because a core version has not been specified in the .info file.');
+        }
+        elseif ($theme->incompatible_core_version) {
+          $output .= t('This version is not compatible with Drupal !core_version and should be replaced.', array('!core_version' => DRUPAL_CORE_COMPATIBILITY));
+        }
+        elseif ($theme->incompatible_core_content) {
+          $output .= t('This version is not compatible with Drupal because the content region has not been specified in the .info file.');
+        }
+        else {
+          $output .= t('This version is not compatible with Drupal.');
+        } 
+        $output .= '</div>';
       }
       elseif (!empty($theme->incompatible_php)) {
         if (substr_count($theme->info['php'], '.') < 2) {