diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..43df993
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "extras"]
+	path = extras
+	url = https://github.com/impress/impress-extras
diff --git a/extras b/extras
new file mode 160000
index 0000000..6230c2f
--- /dev/null
+++ b/extras
@@ -0,0 +1 @@
+Subproject commit 6230c2ff1060f49eedc4ed1d1b8eec7eb30b8ef5