diff --git a/Makefile b/Makefile
index 9cb2a24..8f1e4db 100644
--- a/Makefile
+++ b/Makefile
@@ -21,14 +21,12 @@ help:
 	@echo "Please use \`make <target>' where <target> is one of"
 	@echo "  html            to make standalone HTML files"
 	@echo "  livehtml        to serve the documentation with live reloading"
-	@echo "  clean_sphinx    to remove all built files in docs/"
 	@echo "  clean           to remove all build files and directories (including translations)"
 	@echo "  gettext_build   to build localisation strings for translation"
 	@echo "  update_locale   to update localisation"
 	@echo "  build_html      to build the HTML documentation"
 	@echo "  all             to clean and make all targets"
 	@echo "  copy            to copy docs/index.html to docs/build/html/index.html"
-	@echo "  clean_po        to clean gettext files in .po format"
 
 all: clean_sphinx build_html gettext_build update_locale copy
 
@@ -40,7 +38,7 @@ check:
 	done
 
 copy:
-	cp docs/index.html docs/build/html/index.html
+	cp -p docs/index.html docs/build/html/index.html
 
 html:
 	cd docs && make $(SPHINXOPTS) html