--- a/docs/makefile	Fri Apr 26 01:20:08 2019 +0530
+++ b/docs/makefile	Fri May 03 01:23:12 2019 +0200
@@ -1,6 +1,7 @@
+SPHINXBUILD ?= sphinx-build
 
 all: tutorials/tutorial.rst tutorials/topic-tutorial.rst static/logo-evolve.ico
-	sphinx-build . ../html/
+	$(SPHINXBUILD) . ../html/
 
 tutorials/tutorial.rst: tutorials/tutorial.t test2rst.py
 	python test2rst.py tutorials/
@@ -10,5 +11,3 @@
 
 static/logo-evolve.ico: static/logo-evolve.svg
 	convert -resize 36x36 static/logo-evolve.svg static/logo-evolve.ico
-
-