diff --git a/include/wx/gtk/radiobox.h b/include/wx/gtk/radiobox.h
index 244dbab904..08dc999f55 100644
--- a/include/wx/gtk/radiobox.h
+++ b/include/wx/gtk/radiobox.h
@@ -133,13 +133,8 @@ protected:
     // common part of all ctors
     void Init();
 
-    // check that the index is valid
-    // FIXME: remove once GTK will derive from wxRadioBoxBase
-    inline bool IsValid(int n) const { return n >= 0 && n < GetCount(); }
-
 private:
     DECLARE_DYNAMIC_CLASS(wxRadioBox)
 };
 
 #endif // _WX_GTK_RADIOBOX_H_
-
diff --git a/include/wx/gtk1/radiobox.h b/include/wx/gtk1/radiobox.h
index 4e45065d22..3327b78cdb 100644
--- a/include/wx/gtk1/radiobox.h
+++ b/include/wx/gtk1/radiobox.h
@@ -129,13 +129,8 @@ protected:
     // common part of all ctors
     void Init();
 
-    // check that the index is valid
-    // FIXME: remove once GTK will derive from wxRadioBoxBase
-    inline bool IsValid(int n) const { return n >= 0 && n < GetCount(); }
-
 private:
     DECLARE_DYNAMIC_CLASS(wxRadioBox)
 };
 
 #endif // _WX_GTK_RADIOBOX_H_
-