Index: /trunk/doc/manual/Makefile.kmk
===================================================================
--- /trunk/doc/manual/Makefile.kmk	(revision 56498)
+++ /trunk/doc/manual/Makefile.kmk	(revision 56499)
@@ -665,5 +665,5 @@
 $$(addprefix $(VBOX_PATH_MANUAL_OUTBASE)/$(lang)/,$(VBOX_MANUAL_XML_FILES_INCL_CHANGELOG)) \
 		$$(MAKEFILE_CURRENT)
-	$$(QUIET)xmllint --dtdvalid $$(VBOX_PATH_DOCBOOK_DTD)/docbookx.dtd --xinclude --noout $$<
+	$$(QUIET)xmllint --dtdvalid $$(VBOX_PATH_DOCBOOK_DTD)/docbookx.dtd --xinclude --noout $$(filter %.xml,$$^)
 endef
 
@@ -716,5 +716,5 @@
 validatesdkref: $(addprefix $(VBOX_PATH_MANUAL_OUTBASE)/en_US/,$(VBOX_SDKREF_XML_FILES)) \
 		$(MAKEFILE_CURRENT)
-	$(QUIET)xmllint --dtdvalid $(VBOX_PATH_DOCBOOK_DTD)/docbookx.dtd --xinclude --noout $<
+	$(QUIET)xmllint --dtdvalid $(VBOX_PATH_DOCBOOK_DTD)/docbookx.dtd --xinclude --noout $(filter %.xml,$^)
 
 
@@ -932,5 +932,5 @@
 validateman: $(addprefix $(VBOX_PATH_MANUAL_SRC)/en_US/,$(VBOX_MANUAL_XML_REFENTRY_FILES)) \
 		$(MAKEFILE_CURRENT)
-	$(QUIET)xmllint --dtdvalid $(VBOX_PATH_DOCBOOK_DTD)/docbookx.dtd --noout $<
+	$(QUIET)xmllint --dtdvalid $(VBOX_PATH_DOCBOOK_DTD)/docbookx.dtd --noout $(filter %.xml,$^)