diff --git a/gui/qt/qrtextedit.py b/gui/qt/qrtextedit.py
index eb9e8bf90ca7..66def42c8909 100644
--- a/gui/qt/qrtextedit.py
+++ b/gui/qt/qrtextedit.py
@@ -56,6 +56,8 @@ def qr_input(self):
         except BaseException as e:
             self.show_error(str(e))
             data = ''
+        if not data:
+            data = ''
         self.setText(data)
         return data
 
diff --git a/lib/qrscanner.py b/lib/qrscanner.py
index f659d5e46c11..7516d55d5716 100644
--- a/lib/qrscanner.py
+++ b/lib/qrscanner.py
@@ -49,7 +49,8 @@ def scan_barcode(device='', timeout=-1, display=True, threaded=False):
     libzbar.zbar_symbol_set_first_symbol.restype = ctypes.POINTER(ctypes.c_int)
     proc = libzbar.zbar_processor_create(threaded)
     libzbar.zbar_processor_request_size(proc, 640, 480)
-    libzbar.zbar_processor_init(proc, device, display)
+    if libzbar.zbar_processor_init(proc, device.encode('utf-8'), display) != 0:
+        raise RuntimeError("Can not start QR scanner; initialization failed.")
     libzbar.zbar_processor_set_visible(proc)
     if libzbar.zbar_process_one(proc, timeout):
         symbols = libzbar.zbar_processor_get_results(proc)