diff --git a/trezorlib/transport_hid.py b/trezorlib/transport_hid.py
index a93d12bb76..bb1f9adf9e 100644
--- a/trezorlib/transport_hid.py
+++ b/trezorlib/transport_hid.py
@@ -31,7 +31,7 @@ class HidTransport(Transport):
         # decide if the HID interface is normal transport
         # or debuglink
         
-        if platform.system() in ('Linux', 'Darwin'):
+        if platform.system() == 'Linux':
             # Sample: 0003:0017:00
             if path.endswith(':00'):
                 return False
@@ -44,6 +44,10 @@ class HidTransport(Transport):
                 return True
             return False
 
+        elif platform.system() == 'Darwin':
+            # DebugLink doesn't work on Mac
+            return False
+
         else:
             raise Exception("USB interface detection not implemented for %s" % platform.system())
 
@@ -56,6 +60,11 @@ class HidTransport(Transport):
             serial_number = d['serial_number']
             path = d['path']
 
+            # HIDAPI on Mac cannot detect correct HID interfaces, so device with
+            # DebugLink doesn't work on Mac...
+            if devices.get(serial_number) != None and devices[serial_number][0] == path:
+                raise Exception("Two devices with the same path and S/N found. This is Mac, right? :-/")
+
             if (vendor_id, product_id) in DEVICE_IDS:
                 devices.setdefault(serial_number, [None, None])
                 devices[serial_number][int(bool(cls._detect_debuglink(path)))] = path