diff --git a/meshroom/processGraph/desc.py b/meshroom/processGraph/desc.py
old mode 100644
new mode 100755
index 653acc03..9ecacfdc
--- a/meshroom/processGraph/desc.py
+++ b/meshroom/processGraph/desc.py
@@ -1,5 +1,5 @@
 
-class Attribute:
+class Attribute(object):
     """
     """
     isOutput = False
@@ -26,7 +26,7 @@ class ParamAttribute(Attribute):
         super(ParamAttribute, self).__init__(**kwargs)
 
 
-class Node:
+class Node(object):
     """
     """
     internalFolder = '{nodeType}/{uid0}/'
diff --git a/meshroom/ui/commands.py b/meshroom/ui/commands.py
index f28d1c02..5446a474 100644
--- a/meshroom/ui/commands.py
+++ b/meshroom/ui/commands.py
@@ -21,10 +21,12 @@ class UndoCommand(QUndoCommand):
             return
         self.undoImpl()
 
-    def redoImpl(self) -> bool:
+    def redoImpl(self):
+        # type: () -> bool
         pass
 
-    def undoImpl(self) -> bool:
+    def undoImpl(self):
+        # type: () -> bool
         pass
 
 
@@ -38,7 +40,8 @@ class UndoStack(QUndoStack):
         self.undoTextChanged.connect(self._undoTextChanged)
         self.redoTextChanged.connect(self._redoTextChanged)
 
-    def tryAndPush(self, command: UndoCommand):
+    def tryAndPush(self, command):
+        # type: (UndoCommand) -> bool
         if command.redoImpl():
             command.setEnabled(False)
             self.push(command)  # takes ownership