diff --git a/include/wx/choicebk.h b/include/wx/choicebk.h
index 32092c5631..d85f1f5c4c 100644
--- a/include/wx/choicebk.h
+++ b/include/wx/choicebk.h
@@ -93,7 +93,7 @@ protected:
 
     void UpdateSelectedPage(size_t newsel)
     {
-        m_selection = newsel;
+        m_selection = static_cast<int>(newsel);
         GetChoiceCtrl()->Select(newsel);
     }