diff --git a/README.rst b/README.rst
index 5c0c33d5..eadc49cf 100644
--- a/README.rst
+++ b/README.rst
@@ -119,6 +119,15 @@ Open cmd and go to the `labelImg <#labelimg>`__ directory
     python labelImg.py
     python labelImg.py [IMAGE_PATH] [PRE-DEFINED CLASS FILE]
 
+If you want to package it into a separate EXE file
+
+.. code:: shell
+
+    Install pyinstaller and execute:
+    
+    pip install pyinstaller
+    pyinstaller --hidden-import=pyqt5 --hidden-import=lxml -F -n "labelImg" -c labelImg.py -p ./libs -p ./
+
 Windows + Anaconda
 ^^^^^^^^^^^^^^^^^^
 
diff --git a/labelImg.py b/labelImg.py
index a19a11f7..053cde0c 100755
--- a/labelImg.py
+++ b/labelImg.py
@@ -109,7 +109,10 @@ class MainWindow(QMainWindow, WindowMixin):
         # Load predefined classes to the list
         self.load_predefined_classes(default_prefdef_class_file)
 
-        self.default_label = self.label_hist[0]
+        if self.label_hist:
+            self.default_label = self.label_hist[0]
+        else:
+            print("Not find:/data/predefined_classes.txt (optional)")
 
         # Main widgets and related state.
         self.label_dialog = LabelDialog(parent=self, list_item=self.label_hist)