diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..e997bc5
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "subprojects/test.h"]
+	path = subprojects/test.h
+	url = https://github.com/yshui/test.h
diff --git a/subprojects/test.h b/subprojects/test.h
new file mode 160000
index 0000000..a84877d
--- /dev/null
+++ b/subprojects/test.h
@@ -0,0 +1 @@
+Subproject commit a84877df68873f80ff3620f4993619b35b21f758