diff --git a/.gitmodules b/.gitmodules
index 60e6865..7e6e77c 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -84,3 +84,6 @@
 [submodule "2021/rien"]
 	path = 2021/rien
 	url = git@github.com:rien/adventofcode2021.git
+[submodule "2021/iasoon"]
+	path = 2021/iasoon
+	url = https://github.com/iasoon/aoc2021
diff --git a/2021/iasoon b/2021/iasoon
new file mode 160000
index 0000000..83bb06a
--- /dev/null
+++ b/2021/iasoon
@@ -0,0 +1 @@
+Subproject commit 83bb06a139e199ce34b3f9c4180ecfbd05212143