diff --git a/modules/wps/commerce_paypal_wps.module b/modules/wps/commerce_paypal_wps.module
index 1e6146d..19b6c16 100644
--- a/modules/wps/commerce_paypal_wps.module
+++ b/modules/wps/commerce_paypal_wps.module
@@ -161,7 +161,7 @@ function commerce_paypal_wps_redirect_form_validate($order, $payment_method) {
 function commerce_paypal_wps_paypal_ipn_validate($order, $payment_method, $ipn) {
   // Return FALSE if the receiver e-mail does not match the one specified by
   // the payment method instance.
-  if ($ipn['receiver_email'] != $payment_method['settings']['business']) {
+  if (strtolower($ipn['receiver_email']) != strtolower($payment_method['settings']['business'])) {
     commerce_payment_redirect_pane_previous_page($order);
     watchdog('commerce_paypal_wps', 'IPN rejected: invalid receiver e-mail specified (@receiver_email).', array('@receiver_email' => $ipn['receiver_email']), WATCHDOG_NOTICE);
     return FALSE;