diff --git a/Makefile b/Makefile
index 98fc69a2acf336523fdc1c2c80a1d1efa4f8cd4a..f9b3ded0306a549d3fa7cc91050e6b80f2fc3ba3 100644
--- a/Makefile
+++ b/Makefile
@@ -504,7 +504,7 @@ ifeq ($(XMLSTARLET),:)
 	@echo "--- Please install xmlstarlet to validate the documentation ---"
 	@echo "---------------------------------------------------------------"
 else
-	$(XMLSTARLET) val $<
+	$(XMLSTARLET) val -d doc/appdocsxml.dtd $<
 endif
 
 update: