diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..121c54c
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "external/bmi-example-cxx"]
+	path = external/bmi-example-cxx
+	url = https://github.com/csdms/bmi-example-cxx
diff --git a/external/bmi-example-cxx b/external/bmi-example-cxx
new file mode 160000
index 0000000..d2b0a7f
--- /dev/null
+++ b/external/bmi-example-cxx
@@ -0,0 +1 @@
+Subproject commit d2b0a7f4a6f1857eff05c49844cfeb5fd7ee40ab