diff --git a/XML/src/ParserEngine.h b/XML/src/ParserEngine.h
index f74b553..c638778 100644
--- a/XML/src/ParserEngine.h
+++ b/XML/src/ParserEngine.h
@@ -19,6 +19,7 @@
 
 #include "Poco/XML/XML.h"
 #if defined(POCO_UNBUNDLED)
+#include <expat_config.h>
 #include <expat.h>
 #else
 #include "expat.h"