diff --git a/vncviewer/OptionsDialog.cxx b/vncviewer/OptionsDialog.cxx
index 20465b5..ca5572b 100644
--- a/vncviewer/OptionsDialog.cxx
+++ b/vncviewer/OptionsDialog.cxx
@@ -16,6 +16,10 @@
  * USA.
  */
 
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
 #include <stdlib.h>
 
 #include <list>