diff --git a/include/wx/evtloopsrc.h b/include/wx/evtloopsrc.h
index 0a5d7670cb..227583b776 100644
--- a/include/wx/evtloopsrc.h
+++ b/include/wx/evtloopsrc.h
@@ -11,6 +11,9 @@
 #ifndef _WX_EVTLOOPSRC_H_
 #define _WX_EVTLOOPSRC_H_
 
+// Include the header to get wxUSE_EVENTLOOP_SOURCE definition from it.
+#include "wx/evtloop.h"
+
 // ----------------------------------------------------------------------------
 // wxEventLoopSource: a source of events which may be added to wxEventLoop
 // ----------------------------------------------------------------------------