diff --git a/doc/Makefile b/doc/Makefile
index 73658c9..8ae0eab 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -3,7 +3,7 @@
 
 # You can set these variables from the command line.
 SPHINXOPTS    =
-SPHINXBUILD   = sphinx-build
+SPHINXBUILD   = sphinx-build-3
 PAPER         =
 BUILDDIR      = _build