diff --git a/include/wx/generic/richmsgdlgg.h b/include/wx/generic/richmsgdlgg.h
index fdff492ec3..9d031df435 100644
--- a/include/wx/generic/richmsgdlgg.h
+++ b/include/wx/generic/richmsgdlgg.h
@@ -28,12 +28,7 @@ public:
           m_detailsPane(NULL)
     { }
 
-    virtual bool IsCheckBoxChecked() const
-    {
-        // This function can be called before the dialog is shown and hence
-        // before the check box is created.
-        return m_checkBox? m_checkBoxValue : m_checkBox->IsChecked();
-    }
+    virtual bool IsCheckBoxChecked() const;
 
 protected:
     wxCheckBox *m_checkBox;
diff --git a/src/generic/richmsgdlgg.cpp b/src/generic/richmsgdlgg.cpp
index 9f2efd9e51..06b226d4f6 100644
--- a/src/generic/richmsgdlgg.cpp
+++ b/src/generic/richmsgdlgg.cpp
@@ -18,6 +18,7 @@
 #if wxUSE_RICHMSGDLG
 
 #ifndef WX_PRECOMP
+    #include "wx/checkbox.h"
     #include "wx/stattext.h"
     #include "wx/sizer.h"
 #endif
@@ -84,4 +85,11 @@ void wxGenericRichMessageDialog::AddMessageDialogDetails(wxSizer *sizer)
     }
 }
 
+bool wxGenericRichMessageDialog::IsCheckBoxChecked() const
+{
+    // This function can be called before the dialog is shown and hence before
+    // the check box is created.
+    return m_checkBox? m_checkBoxValue : m_checkBox->IsChecked();
+}
+
 #endif // wxUSE_RICHMSGDLG