diff --git a/cores/arduino/USBCore.h b/cores/arduino/USBCore.h
index 530abec..4e08d71 100644
--- a/cores/arduino/USBCore.h
+++ b/cores/arduino/USBCore.h
@@ -49,9 +49,9 @@
 #define REQUEST_OTHER			0x03
 #define REQUEST_RECIPIENT		0x03
 
-#define REQUEST_DEVICETOHOST_CLASS_INTERFACE    (REQUEST_DEVICETOHOST + REQUEST_CLASS + REQUEST_INTERFACE)
-#define REQUEST_HOSTTODEVICE_CLASS_INTERFACE    (REQUEST_HOSTTODEVICE + REQUEST_CLASS + REQUEST_INTERFACE)
-#define REQUEST_DEVICETOHOST_STANDARD_INTERFACE (REQUEST_DEVICETOHOST + REQUEST_STANDARD + REQUEST_INTERFACE)
+#define REQUEST_DEVICETOHOST_CLASS_INTERFACE    (REQUEST_DEVICETOHOST | REQUEST_CLASS | REQUEST_INTERFACE)
+#define REQUEST_HOSTTODEVICE_CLASS_INTERFACE    (REQUEST_HOSTTODEVICE | REQUEST_CLASS | REQUEST_INTERFACE)
+#define REQUEST_DEVICETOHOST_STANDARD_INTERFACE (REQUEST_DEVICETOHOST | REQUEST_STANDARD | REQUEST_INTERFACE)
 
 //	Class requests