diff --git a/includes/bootstrap.inc b/includes/bootstrap.inc
index 03e5880..196e683 100644
--- a/includes/bootstrap.inc
+++ b/includes/bootstrap.inc
@@ -898,8 +898,29 @@ function variable_initialize($conf = array()) {
     }
     else {
       // Proceed with variable rebuild.
-      $variables = array_map('unserialize', db_query('SELECT name, value FROM {variable}')->fetchAllKeyed());
-      cache_set('variables', $variables, 'cache_bootstrap');
+      $variables = array();
+      // We can run into unparsable values
+      $err_variables = array();
+      $rows = db_query('SELECT name, value FROM {variable}')->fetchAllKeyed();
+      foreach ($rows as $name => $db_value) {
+        // Suppress the notice.
+        $value = @unserialize($db_value);
+        // If the unserialize call returned FALSE and the stored value is NOT a
+        // boolean false, list it in the report.
+        if ($value === FALSE && $db_value != serialize(FALSE) && !isset($conf[$name])) {
+          $err_variables[] = $name;
+        }
+        $variables[$name] = $value;
+      }
+      // We throw an exception before storing the variables otherwise
+      // this exception is only thrown once which is bad.
+      if (count($err_variables)) {
+        $t = get_t();
+        $err_vars = join (", ", $err_variables);
+        $err_str = "The variable(s) '@err_vars' are unreadable and need to be fixed. Please read UPGRADE.txt on how to resolve this problem.";
+        throw new Exception($t($err_str, array('@err_vars' => $err_vars)));
+      }
+      cache('bootstrap')->set('variables', $variables);
       lock_release($name);
     }
   }
diff --git a/modules/simpletest/tests/bootstrap.test b/modules/simpletest/tests/bootstrap.test
index 014fc94..7ebdc82 100644
--- a/modules/simpletest/tests/bootstrap.test
+++ b/modules/simpletest/tests/bootstrap.test
@@ -267,6 +267,35 @@ class BootstrapVariableTestCase extends DrupalWebTestCase {
     $this->assertIdentical(5, variable_get('simpletest_bootstrap_variable_test', 5), t('The default variable parameter is passed through correctly.'));
   }
 
+  /**
+   * Test for a corrupted variable.
+   */
+  function testFaultyVariable() {
+    $name = 'simpletest_bootstrap_wrong_variable_test';
+    $test_value = 'unserialized_value';
+
+    // We write a value directly to the database bypassing the serialization
+    // We cannot use drupal_write_record as that serializes the value
+    db_merge('variable')->key(array('name' => $name))->fields(array('value' => $test_value))->execute();
+
+    // Clear the variable cache to reread the new value
+    cache_clear_all('variables', 'cache_bootstrap');
+    // Reseed the variables. This should load $name
+    variable_initialize();
+
+    // Value should be 'default_value'.
+    $value = variable_get($name, 'default_value');
+    $this->assertNotEqual($value, $test_value, 'Variable set incorrectly returned default value');
+
+    // Show that when variable is set correctly it returns correctly.
+    variable_set($name, $test_value);
+
+    cache_clear_all('variables', 'cache_bootstrap');
+    variable_initialize();
+
+    $value = variable_get($name, 'default_value');
+    $this->assertEqual($value, $test_value, 'Variable set correctly returns correct data');
+  }
 }
 
 /**