diff --git a/env/bin/enhancer.py b/env/bin/enhancer.py
index 4afe4b88..9bf13fce 100755
--- a/env/bin/enhancer.py
+++ b/env/bin/enhancer.py
@@ -21,8 +21,8 @@
 
 
 class Enhance(tkinter.Frame):
-    def __init__(self, master, image, name, enhancer, lo, hi):
-        tkinter.Frame.__init__(self, master)
+    def __init__(self, main, image, name, enhancer, lo, hi):
+        tkinter.Frame.__init__(self, main)
 
         # set up the image
         self.tkim = ImageTk.PhotoImage(image.mode, image.size)
diff --git a/env/bin/painter.py b/env/bin/painter.py
index d5b6e0df..c48e0555 100755
--- a/env/bin/painter.py
+++ b/env/bin/painter.py
@@ -23,8 +23,8 @@
 
 
 class PaintCanvas(tkinter.Canvas):
-    def __init__(self, master, image):
-        tkinter.Canvas.__init__(self, master,
+    def __init__(self, main, image):
+        tkinter.Canvas.__init__(self, main,
                                 width=image.size[0], height=image.size[1])
 
         # fill the canvas
diff --git a/env/bin/player.py b/env/bin/player.py
index 9ea8a34a..fef60796 100755
--- a/env/bin/player.py
+++ b/env/bin/player.py
@@ -21,7 +21,7 @@
 
 class UI(tkinter.Label):
 
-    def __init__(self, master, im):
+    def __init__(self, main, im):
         if isinstance(im, list):
             # list of images
             self.im = im[1:]
@@ -35,7 +35,7 @@ def __init__(self, master, im):
         else:
             self.image = ImageTk.PhotoImage(im)
 
-        tkinter.Label.__init__(self, master, image=self.image, bg="black", bd=0)
+        tkinter.Label.__init__(self, main, image=self.image, bg="black", bd=0)
 
         self.update()
 
diff --git a/env/bin/thresholder.py b/env/bin/thresholder.py
index 9a4ca416..f1de5aee 100755
--- a/env/bin/thresholder.py
+++ b/env/bin/thresholder.py
@@ -21,8 +21,8 @@
 
 
 class UI(tkinter.Frame):
-    def __init__(self, master, im, value=128):
-        tkinter.Frame.__init__(self, master)
+    def __init__(self, main, im, value=128):
+        tkinter.Frame.__init__(self, main)
 
         self.image = im
         self.value = value
diff --git a/env/bin/viewer.py b/env/bin/viewer.py
index 9c11db40..08d2d3a1 100755
--- a/env/bin/viewer.py
+++ b/env/bin/viewer.py
@@ -21,18 +21,18 @@
 
 class UI(tkinter.Label):
 
-    def __init__(self, master, im):
+    def __init__(self, main, im):
 
         if im.mode == "1":
             # bitmap image
             self.image = ImageTk.BitmapImage(im, foreground="white")
-            tkinter.Label.__init__(self, master, image=self.image, bd=0,
+            tkinter.Label.__init__(self, main, image=self.image, bd=0,
                                    bg="black")
 
         else:
             # photo image
             self.image = ImageTk.PhotoImage(im)
-            tkinter.Label.__init__(self, master, image=self.image, bd=0)
+            tkinter.Label.__init__(self, main, image=self.image, bd=0)
 
 #
 # script interface