diff --git a/kcc/KCC_gui.py b/kcc/KCC_gui.py
index 75d3aff..33c05a9 100644
--- a/kcc/KCC_gui.py
+++ b/kcc/KCC_gui.py
@@ -506,7 +506,7 @@ class WorkerThread(QtCore.QThread):
                         self.pool.waitForDone()
                         sleep(0.5)
                         for success in self.workerOutput:
-                            if not success:
+                            if not success[0]:
                                 self.errors = True
                                 break
                         if not self.errors:
diff --git a/kcc/dualmetafix.py b/kcc/dualmetafix.py
index b8c3d06..7678931 100644
--- a/kcc/dualmetafix.py
+++ b/kcc/dualmetafix.py
@@ -140,7 +140,7 @@ class DualMobiMetaFix:
         self.datain = open(infile, 'rb').read()
         self.datain_rec0 = readsection(self.datain, 0)
         # noinspection PyArgumentList
-        self.asin = bytes(uuid4(), 'UTF-8')
+        self.asin = bytes(str(uuid4()), 'UTF-8')
 
         # in the first mobi header
         # add 501 to "EBOK", add 113 as asin, add 504 as asin