diff --git a/src/ftdipp_mpsse.cpp b/src/ftdipp_mpsse.cpp
index 81c6ece..0c13a4e 100644
--- a/src/ftdipp_mpsse.cpp
+++ b/src/ftdipp_mpsse.cpp
@@ -173,7 +173,7 @@ void FTDIpp_MPSSE::open_device(const std::string &serial, unsigned int baudrate)
 		throw std::runtime_error(err);
 	}
 
-	if (_bus == 0 || _addr == 0)
+	if (_bus == 0 && _addr == 0)
 		ret = ftdi_usb_open_desc_index(_ftdi, _vid, _pid, NULL, serial.empty() ? NULL : serial.c_str(), _index);
 	else
 #if (FTDI_VERSION < 104)
diff --git a/src/libusb_ll.cpp b/src/libusb_ll.cpp
index ce5915f..c7cc966 100644
--- a/src/libusb_ll.cpp
+++ b/src/libusb_ll.cpp
@@ -57,7 +57,7 @@ int libusb_ll::get_devices_list(const cable_t *cable)
 		bus_addr = cable->bus_addr;
 		device_addr = cable->device_addr;
 		vid_pid_filter = (vid != 0) && (pid != 0);
-		bus_dev_filter = (bus_addr != 0) && (device_addr != 0);
+		bus_dev_filter = ~(bus_addr == 0 && device_addr == 0);
 	}
 
 	int i = 0;