diff --git a/docs/Makefile b/docs/Makefile
index d0df30f99..d47df9de2 100644
--- a/docs/Makefile
+++ b/docs/Makefile
@@ -2,11 +2,11 @@
 #
 
 # You can set these variables from the command line, and also
-# from the environment for the first two.
+# from the environment for the first three.
 SPHINXOPTS    ?=
 SPHINXBUILD   ?= sphinx-build
+BUILDDIR      ?= build
 SOURCEDIR     = src
-BUILDDIR      = build
 
 # Put it first so that "make" without argument is like "make help".
 help:
diff --git a/docs/make.bat b/docs/make.bat
index fa71760f6..4f7e43932 100644
--- a/docs/make.bat
+++ b/docs/make.bat
@@ -7,8 +7,10 @@ REM Command file for Sphinx documentation
 if "%SPHINXBUILD%" == "" (
 	set SPHINXBUILD=sphinx-build
 )
+if "%BUILDDIR%" == "" (
+	set BUILDDIR=build
+)
 set SOURCEDIR=src
-set BUILDDIR=build
 
 if "%1" == "" goto help