diff --git a/libusb/os/darwin_usb.c b/libusb/os/darwin_usb.c
index e415589d670f071e6acb03247ba7b448fdb1e096..9fdc4bbc6b70770a5cddd1f19972b17219f55d3f 100644
--- a/libusb/os/darwin_usb.c
+++ b/libusb/os/darwin_usb.c
@@ -2148,7 +2148,7 @@ static int darwin_handle_transfer_completion (struct usbi_transfer *itransfer) {
   struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
   struct darwin_transfer_priv *tpriv = usbi_get_transfer_priv(itransfer);
   const unsigned char max_transfer_type = LIBUSB_TRANSFER_TYPE_BULK_STREAM;
-  const char *transfer_types[max_transfer_type + 1] = {"control", "isoc", "bulk", "interrupt", "bulk-stream"};
+  const char *transfer_types[LIBUSB_TRANSFER_TYPE_BULK_STREAM + 1] = {"control", "isoc", "bulk", "interrupt", "bulk-stream"};
   bool is_isoc = LIBUSB_TRANSFER_TYPE_ISOCHRONOUS == transfer->type;
 
   if (transfer->type > max_transfer_type) {