diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 000000000..53ea83f85
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "docs/en/_theme"]
+    path = docs/en/_theme
+    url = git://github.com/doctrine/doctrine-sphinx-theme.git