diff --git a/Documentation/Makefile b/Documentation/Makefile
index d77bb60..79ecee6 100644
--- a/Documentation/Makefile
+++ b/Documentation/Makefile
@@ -13,7 +13,7 @@
 SPHINXBUILD   = sphinx-build
 SPHINXOPTS    =
 SPHINXDIRS    = .
-_SPHINXDIRS   = $(patsubst $(srctree)/Documentation/%/index.rst,%,$(wildcard $(srctree)/Documentation/*/index.rst))
+_SPHINXDIRS   = $(sort $(patsubst $(srctree)/Documentation/%/index.rst,%,$(wildcard $(srctree)/Documentation/*/index.rst)))
 SPHINX_CONF   = conf.py
 PAPER         =
 BUILDDIR      = $(obj)/output