diff --git a/src/main/edu/wisc/services/cbs/order/interfacing/MockOrderInterfacingService.php b/src/main/edu/wisc/services/cbs/order/interfacing/MockOrderInterfacingService.php
index 017ae868f1aef7428153c0fa36dabf7b34f7c9a3..72350188666308a47370047d6b9c6411c958b5c7 100644
--- a/src/main/edu/wisc/services/cbs/order/interfacing/MockOrderInterfacingService.php
+++ b/src/main/edu/wisc/services/cbs/order/interfacing/MockOrderInterfacingService.php
@@ -30,7 +30,7 @@ class MockOrderInterfacingService implements OrderInterfacingService, MockServic
     /**
      * {@inheritdoc}
      */
-    public function interfaceOrder($orderNumber)
+    public function interfaceOrder($orderNumber): OrderServiceResponse
     {
         return $this->response;
     }
diff --git a/src/main/edu/wisc/services/cbs/order/interfacing/OrderInterfacingService.php b/src/main/edu/wisc/services/cbs/order/interfacing/OrderInterfacingService.php
index da2fd00ec56eae6b23e06b17af5e006f08bb78ac..fd65296d46b1dc4071d5023cd2beb5013775447e 100644
--- a/src/main/edu/wisc/services/cbs/order/interfacing/OrderInterfacingService.php
+++ b/src/main/edu/wisc/services/cbs/order/interfacing/OrderInterfacingService.php
@@ -13,9 +13,9 @@ interface OrderInterfacingService extends Service
 
     /**
      * Commit and finalize ("interface") an order with CBS.
-     * @param string $orderNumber
+     * @param float $orderNumber
      * @return OrderServiceResponse
      */
-    public function interfaceOrder($orderNumber);
+    public function interfaceOrder($orderNumber): OrderServiceResponse;
 
 }
\ No newline at end of file
diff --git a/src/main/edu/wisc/services/cbs/order/interfacing/SoapOrderInterfacingService.php b/src/main/edu/wisc/services/cbs/order/interfacing/SoapOrderInterfacingService.php
index 27a070a8c1bc2cd2f567b84f3f8fa5ef440e17cb..300e3992bd1f47823a0b0d45f6da8d9d8dc0ed19 100644
--- a/src/main/edu/wisc/services/cbs/order/interfacing/SoapOrderInterfacingService.php
+++ b/src/main/edu/wisc/services/cbs/order/interfacing/SoapOrderInterfacingService.php
@@ -45,7 +45,10 @@ class SoapOrderInterfacingService implements OrderInterfacingService, SoapServic
         }
     }
 
-    public function interfaceOrder($orderNumber)
+    /**
+     * {@inheritdoc}
+     */
+    public function interfaceOrder($orderNumber): OrderServiceResponse
     {
         $response = $this->soapClient->INTERFACE_ORDER(
             new InputParameters($orderNumber, "MAGE$orderNumber", 'TBD')