diff --git a/registrasion/controllers/invoice.py b/registrasion/controllers/invoice.py
index 3b675e17..7b35ea58 100644
--- a/registrasion/controllers/invoice.py
+++ b/registrasion/controllers/invoice.py
@@ -331,10 +331,7 @@ class InvoiceController(ForId, object):
     def _mark_refunded(self):
         ''' Marks the invoice as refunded, and updates the attached cart if
         necessary. '''
-        cart = self.invoice.cart
-        if cart:
-            cart.status = commerce.Cart.STATUS_RELEASED
-            cart.save()
+        self._release_cart()
         self.invoice.status = commerce.Invoice.STATUS_REFUNDED
         self.invoice.save()
 
@@ -356,6 +353,12 @@ class InvoiceController(ForId, object):
 
         return cart.revision == self.invoice.cart_revision
 
+    def _release_cart(self):
+        cart = self.invoice.cart
+        if cart:
+            cart.status = commerce.Cart.STATUS_RELEASED
+            cart.save()
+
     def update_validity(self):
         ''' Voids this invoice if the attached cart is no longer valid because
         the cart revision has changed, or the reservations have expired. '''
@@ -381,6 +384,9 @@ class InvoiceController(ForId, object):
             raise ValidationError("Invoices with payments must be refunded.")
         elif self.invoice.is_refunded:
             raise ValidationError("Refunded invoices may not be voided.")
+        if self.invoice.is_paid:
+            self._release_cart()
+
         self._mark_void()
 
     @transaction.atomic
diff --git a/registrasion/tests/test_invoice.py b/registrasion/tests/test_invoice.py
index 50790874..61e1abc9 100644
--- a/registrasion/tests/test_invoice.py
+++ b/registrasion/tests/test_invoice.py
@@ -142,7 +142,7 @@ class InvoiceTestCase(TestHelperMixin, RegistrationCartTestCase):
             self.PROD_1.price * Decimal("0.5"),
             invoice_1.invoice.value)
 
-    def test_zero_value_invoice_is_automatically_paid(self):
+    def _make_zero_value_invoice(self):
         voucher = inventory.Voucher.objects.create(
             recipient="Voucher recipient",
             code="VOUCHER",
@@ -164,10 +164,21 @@ class InvoiceTestCase(TestHelperMixin, RegistrationCartTestCase):
 
         # Should be able to create an invoice after the product is added
         current_cart.add_to_cart(self.PROD_1, 1)
-        invoice_1 = TestingInvoiceController.for_cart(current_cart.cart)
+        return TestingInvoiceController.for_cart(current_cart.cart)
 
+
+    def test_zero_value_invoice_is_automatically_paid(self):
+        invoice_1 = self._make_zero_value_invoice()
         self.assertTrue(invoice_1.invoice.is_paid)
 
+    def test_refunding_zero_value_invoice_releases_cart(self):
+        invoice_1 = self._make_zero_value_invoice()
+        cart = invoice_1.invoice.cart
+        invoice_1.refund()
+
+        cart.refresh_from_db()
+        self.assertEquals(commerce.Cart.STATUS_RELEASED, cart.status)
+
     def test_invoice_voids_self_if_cart_changes(self):
         current_cart = TestingCartController.for_user(self.USER_1)