diff --git a/qubesusbproxy/core3ext.py b/qubesusbproxy/core3ext.py
index 799bff6..a5ab155 100644
--- a/qubesusbproxy/core3ext.py
+++ b/qubesusbproxy/core3ext.py
@@ -642,9 +642,10 @@ async def on_device_attach_usb(self, vm, event, device, options):
                 else:
                     # TODO: sanitize and include stdout
                     sanitized_stderr = ''.join(
-                        [chr(c) for c in e.stderr if 0x20 <= c < 0x80])
+                        [chr(c) for c in e.stderr if 0x20 <= c < 0x80
+                         or c in [0x0A, 0x0D]])
                     raise QubesUSBException(
-                        'Device attach failed: {}'.format(sanitized_stderr))
+                        'Device attach failed:\n{}'.format(sanitized_stderr))
         finally:
             modify_qrexec_policy('qubes.USB+{}'.format(device.ident),
                 policy_line, False)