diff --git a/.gitmodules b/.gitmodules
index e69de29..46c24d6 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "external/ctre"]
+	path = external/ctre
+	url = https://github.com/hanickadot/compile-time-regular-expressions.git
diff --git a/external/ctre b/external/ctre
new file mode 160000
index 0000000..626313d
--- /dev/null
+++ b/external/ctre
@@ -0,0 +1 @@
+Subproject commit 626313dd1563e6f3a02e35427052d808df636cd8