diff --git a/doc/Makefile b/doc/Makefile
index c2a7ea9904a50b8f8b0936dd6dabb45112f587a9..d4a5c6a6da02687badc92c0e018b9f3f0cdde6d5 100644
--- a/doc/Makefile
+++ b/doc/Makefile
@@ -3,7 +3,7 @@
 
 # You can set these variables from the command line.
 SPHINXOPTS    =
-SPHINXBUILD   = python `which sphinx-build`
+SPHINXBUILD   = python3 `which sphinx-build`
 PAPER         =
 BUILDDIR      = _build