diff --git a/src/html/helpctrl.cpp b/src/html/helpctrl.cpp
index 5f0bc3fd68..87be6838d1 100644
--- a/src/html/helpctrl.cpp
+++ b/src/html/helpctrl.cpp
@@ -111,6 +111,8 @@ bool wxHtmlHelpController::AddBook(const wxString& book, bool show_wait_msg)
 #if wxUSE_BUSYINFO
     if (show_wait_msg)
         delete busy;
+#else
+    wxUnusedVar(show_wait_msg);
 #endif
     if (m_helpFrame) 
         m_helpFrame->RefreshLists();