diff --git a/.gitmodules b/.gitmodules
index 781c0a1..1b64bea 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -316,3 +316,6 @@
 [submodule "ruby-ref"]
 	path = ruby-ref
 	url = ssh://aur@aur.archlinux.org/ruby-ref.git
+[submodule "ruby-ddmemoize"]
+	path = ruby-ddmemoize
+	url = ssh://aur@aur.archlinux.org/ruby-ddmemoize.git
diff --git a/ruby-ddmemoize b/ruby-ddmemoize
new file mode 160000
index 0000000..63ae835
--- /dev/null
+++ b/ruby-ddmemoize
@@ -0,0 +1 @@
+Subproject commit 63ae835088a995e208daf8c19433275f2bc4fa66