diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..621a566
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "upstream"]
+	path = upstream
+	url = https://github.com/chriskohlhoff/asio.git
diff --git a/upstream b/upstream
new file mode 160000
index 0000000..c465349
--- /dev/null
+++ b/upstream
@@ -0,0 +1 @@
+Subproject commit c465349fa5cd91a64bb369f5131ceacab2c0c1c3