diff --git a/terminatorlib/layoutlauncher.py b/terminatorlib/layoutlauncher.py
index b4981748..6045b041 100755
--- a/terminatorlib/layoutlauncher.py
+++ b/terminatorlib/layoutlauncher.py
@@ -72,7 +72,7 @@ class LayoutLauncher:
         """Update the contents of the layout"""
         self.layouttreestore.clear()
         layouts = self.config.list_layouts()
-        for layout in sorted(layouts, cmp=lambda x,y: cmp(x.lower(), y.lower())):
+        for layout in sorted(layouts, key=str.lower):
             if layout != "default":
                 self.layouttreestore.append([layout])
             else:
diff --git a/terminatorlib/notebook.py b/terminatorlib/notebook.py
index 000d6f97..6f32cd3b 100755
--- a/terminatorlib/notebook.py
+++ b/terminatorlib/notebook.py
@@ -3,6 +3,7 @@
 # GPL v2 only
 """notebook.py - classes for the notebook widget"""
 
+from functools import cmp_to_key
 from gi.repository import GObject
 from gi.repository import Gtk
 from gi.repository import Gdk
@@ -100,7 +101,7 @@ class Notebook(Container, Gtk.Notebook):
 
         num = 0
         keys = list(children.keys())
-        keys.sort(child_compare)
+        keys = sorted(keys, key=cmp_to_key(child_compare))
 
         for child_key in keys:
             child = children[child_key]