diff --git a/sphinx-docs/Makefile b/sphinx-docs/Makefile
index 914f2f03..5a6d3153 100644
--- a/sphinx-docs/Makefile
+++ b/sphinx-docs/Makefile
@@ -2,6 +2,7 @@
 
 SPHINXOPTS   ?=
 SPHINXBUILD  ?= sphinx-build
+SED          = gsed
 SOURCEDIR    = source
 BUILDDIR     = build
 SITEDIR      = ../docs
@@ -50,8 +51,8 @@ build_manual: gen_html
 	rm "$(MANUALDIR)/index.html"
 	mv "$(MANUALDIR)/contents.html" "$(MANUALDIR)/index.html"
 
-	cd "$(MANUALDIR)" && find . -type f -name '*.html' -exec sed -i 's|contents.html|index.html|g' {} +
-	cd "$(MANUALDIR)" && find . -type f -name '*.html' -exec sed -i 's|<p>Hosted on <a href="https://pages.github.com/">GitHub Pages</a></p>||g' {} + 
+	cd "$(MANUALDIR)" && find . -type f -name '*.html' -exec $(SED) -i 's|contents.html|index.html|g' {} +
+	cd "$(MANUALDIR)" && find . -type f -name '*.html' -exec $(SED) -i 's|<p>Hosted on <a href="https://pages.github.com/">GitHub Pages</a></p>||g' {} + 
 
 
 generate_css: