diff --git a/specs/troffrules.in b/specs/troffrules.in
index af891209..93c56801 100644
--- a/specs/troffrules.in
+++ b/specs/troffrules.in
@@ -44,7 +44,7 @@ MOSTLYCLEANFILES = index.*
 
 # Install html generated images for specs
 install-data-local:
-	test -z "$(imagesdir)" || $(MKDIR_P) "$(DESTDIR)$(imagesdir)"
+	test -z "$(imagesdir)" || $(mkdir_p) "$(DESTDIR)$(imagesdir)"
 	@d="$(srcdir)/images/"; \
 	list=`ls $$d`; \
 	for p in $$list; do \