diff --git a/samples/treectrl/treetest.cpp b/samples/treectrl/treetest.cpp
index 2b46734d3f..9a0b6e0b30 100644
--- a/samples/treectrl/treetest.cpp
+++ b/samples/treectrl/treetest.cpp
@@ -507,6 +507,7 @@ MyTreeCtrl::MyTreeCtrl(wxWindow *parent, const wxWindowID id,
           : wxTreeCtrl(parent, id, pos, size, style)
 {
     m_reverseSort = FALSE;
+    m_imageListNormal = NULL;
 
     CreateImageList();