diff --git a/docs/Makefile b/docs/Makefile
index d4bb2cb..fc8992c 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -4,7 +4,7 @@
 # You can set these variables from the command line, and also
 # from the environment for the first two.
 SPHINXOPTS    ?=
-SPHINXBUILD   ?= sphinx-build
+SPHINXBUILD   ?= /usr/bin/sphinx-build
 SOURCEDIR     = .
 BUILDDIR      = _build