diff --git a/.gitmodules b/.gitmodules
index 2d52e9acd..66db29b07 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -13,3 +13,6 @@
 [submodule "lib/vendor/doctrine-build-common"]
 	path = lib/vendor/doctrine-build-common
 	url = git://github.com/doctrine/doctrine-build-common.git
+[submodule "docs/en/_theme"]
+    path = docs/en/_theme
+    url = git://github.com/doctrine/doctrine-sphinx-theme.git