diff --git a/src/Entity/Currency.php b/src/Entity/Currency.php
index cab74db..a6645d0 100644
--- a/src/Entity/Currency.php
+++ b/src/Entity/Currency.php
@@ -11,7 +11,6 @@ use Drupal\Core\Config\Entity\ConfigEntityBase;
 use Drupal\Core\Entity\EntityManagerInterface;
 use Drupal\Core\Language\LanguageInterface;
 use Drupal\currency\Plugin\Currency\AmountFormatter\AmountFormatterManagerInterface;
-use Drupal\currency\Usage;
 
 /**
  * Defines a currency entity class.
@@ -124,6 +123,13 @@ class Currency extends ConfigEntityBase implements CurrencyInterface {
   protected $subunits;
 
   /**
+   * An array of exchange rates for different currency conversions.
+   *
+   * @var array
+   */
+  protected $exchangeRates;
+
+  /**
    * This currency's usages.
    *
    * @var \Drupal\currency\UsageInterface[]
@@ -141,13 +147,6 @@ class Currency extends ConfigEntityBase implements CurrencyInterface {
    * {@inheritdoc}
    */
   public function __construct(array $values, $entity_type) {
-    if (isset($values['usages'])) {
-      $usages_data = $values['usages'];
-      $values['usages'] = [];
-      foreach ($usages_data as $usage_data) {
-        $values['usages'][] = $usage_data;
-      }
-    }
     parent::__construct($values, $entity_type);
   }
 
@@ -202,6 +201,21 @@ class Currency extends ConfigEntityBase implements CurrencyInterface {
   /**
    * {@inheritdoc}
    */
+  public function getExchangeRates() {
+    return $this->exchangeRates;
+  }
+  /**
+   * {@inheritdoc}
+   */
+  public function setExchangeRates(array $exchange_rates) {
+    $this->exchangeRates = $exchange_rates;
+
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function setLabel($label) {
     $this->label = $label;
 
diff --git a/src/Entity/Currency/CurrencyForm.php b/src/Entity/Currency/CurrencyForm.php
index acff283..8a14270 100644
--- a/src/Entity/Currency/CurrencyForm.php
+++ b/src/Entity/Currency/CurrencyForm.php
@@ -80,6 +80,7 @@ class CurrencyForm extends EntityForm {
     $values = $form_state->getValues();
     $currency->setCurrencyCode($values['currency_code']);
     $currency->setCurrencyNumber($values['currency_number']);
+    $currency->setExchangeRates(array());
     $currency->setLabel($values['label']);
     $currency->setSign($values['sign']);
     $currency->setSubunits($values['subunits']);
@@ -118,6 +119,8 @@ class CurrencyForm extends EntityForm {
       '#type' => 'textfield',
     );
 
+    // @todo add missing UI for exchange rates.
+
     $form['status'] = array(
       '#default_value' => $currency->status(),
       '#title' => $this->t('Enabled'),
diff --git a/src/Entity/CurrencyInterface.php b/src/Entity/CurrencyInterface.php
index 4c47e0b..638022e 100644
--- a/src/Entity/CurrencyInterface.php
+++ b/src/Entity/CurrencyInterface.php
@@ -151,6 +151,20 @@ interface CurrencyInterface extends ConfigEntityInterface {
    */
   public function getDecimals();
 
+
+  /**
+   * Gets the exchange rates for this currency.
+   */
+  public function getExchangeRates();
+
+  /**
+   * Returns the exchange rates for this currency.
+   *
+   * @param array $exchange_rates
+   *   An array with exchange rates from one currency to another.
+   */
+  public function setExchangeRates(array $exchange_rates);
+
   /**
    * Format an amount using this currency and the environment's default currency locale.
    * pattern.
diff --git a/src/Tests/Entity/Currency/CurrencyDeleteFormWebTest.php b/src/Tests/Entity/Currency/CurrencyDeleteFormWebTest.php
index 8f19425..c60ec1e 100644
--- a/src/Tests/Entity/Currency/CurrencyDeleteFormWebTest.php
+++ b/src/Tests/Entity/Currency/CurrencyDeleteFormWebTest.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\currency\Tests\Entity\Currency;
 
+use Drupal\Core\Entity\Entity;
+use Drupal\currency\Entity\Currency;
 use Drupal\simpletest\WebTestBase;
 
 /**
@@ -22,11 +24,12 @@ class CurrencyDeleteFormWebTest extends WebTestBase {
    * Tests the form.
    */
   function testForm() {
-    $user = $this->drupalCreateUser(array('currency.currency.delete'));
+    $user = $this->drupalCreateUser(['currency.currency.delete', 'currency.currency.view']);
     $this->drupalLogin($user);
-    $currency = entity_create('currency', array(
+    $currency = Currency::create([
       'currencyCode' => 'ABC',
-    ));
+      'exchangeRates' => [],
+    ]);
     $currency->save();
     $this->drupalPostForm('admin/config/regional/currency/' . $currency->id() . '/delete', array(), t('Delete'));
     $this->assertFalse((bool) entity_load_unchanged('currency', $currency->id()));