diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..6727298
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "external/highway"]
+	path = external/highway
+	url = https://github.com/google/highway.git
diff --git a/external/highway b/external/highway
new file mode 160000
index 0000000..fa49471
--- /dev/null
+++ b/external/highway
@@ -0,0 +1 @@
+Subproject commit fa49471c43ba37c528dd77b0ef060cdc313054bb