diff --git a/src/gtk/assertdlg_gtk.cpp b/src/gtk/assertdlg_gtk.cpp
index 0deb8617ef..e80caffbdb 100644
--- a/src/gtk/assertdlg_gtk.cpp
+++ b/src/gtk/assertdlg_gtk.cpp
@@ -12,6 +12,8 @@
 #include "wx/gtk/assertdlg_gtk.h"
 #include "wx/gtk/private/gtk2-compat.h"
 
+#include <stdio.h>
+
 /* ----------------------------------------------------------------------------
    Constants
  ---------------------------------------------------------------------------- */