diff --git a/doc/manual/Makefile b/doc/manual/Makefile
index 5fb001472..6da034bc2 100644
--- a/doc/manual/Makefile
+++ b/doc/manual/Makefile
@@ -64,7 +64,7 @@ manual.html: version $(IMAGES) $(CHAPTERS)
 	$(TEXI2HTML) ${CSS} manual.texi
 
 manual/manual.html: version $(IMAGES) $(CHAPTERS)
-	$(TEXI2HTML) ${CSS} ${SPLIT} manual.texi
+	$(TEXI2HTML) ${CSS} ${SPLIT} --output manual manual.texi
 
 figures-clean:
 	rm -rf $(IMAGES)
diff --git a/doc/testing/Makefile b/doc/testing/Makefile
index b533252ff..c22b76e8d 100644
--- a/doc/testing/Makefile
+++ b/doc/testing/Makefile
@@ -34,7 +34,7 @@ testing.html: version $(IMAGES) $(CHAPTERS)
 	$(TEXI2HTML) ${CSS} testing.texi
 
 testing/testing.html: version $(IMAGES) $(CHAPTERS)
-	$(TEXI2HTML) ${CSS} ${SPLIT} testing.texi
+	$(TEXI2HTML) ${CSS} ${SPLIT} --output testing testing.texi
 
 figures-clean:
 	rm -rf $(IMAGES)