diff --git a/java/src/ch/ntb/usb/Device.java b/java/src/ch/ntb/usb/Device.java
index 47650a4..aed65e5 100644
--- a/java/src/ch/ntb/usb/Device.java
+++ b/java/src/ch/ntb/usb/Device.java
@@ -182,7 +182,7 @@ public class Device {
 
 		if (dev != null) {
 			int res = LibusbJava.usb_open(dev);
-			if (res != 0) {
+			if (res == 0) {
 				throw new USBException("LibusbJava.usb_open: "
 						+ LibusbJava.usb_strerror());
 			}