diff --git a/etgtools/tweaker_tools.py b/etgtools/tweaker_tools.py
index 5b76888e4..bdaf35bb6 100644
--- a/etgtools/tweaker_tools.py
+++ b/etgtools/tweaker_tools.py
@@ -331,6 +331,7 @@ def fixSizerClass(klass):
     removeVirtuals(klass)
     klass.find('CalcMin').isVirtual = True
     klass.find('RepositionChildren').isVirtual = True
+    klass.find('InformFirstDirection').isVirtual = True
 
     # in the wxSizer class it is pure-virtual
     if klass.name == 'wxSizer':