diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..786ae53
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "mcalc"]
+	path = mcalc
+	url = https://scm.dairydemon.net/filifa/mcalc
diff --git a/index.html b/index.html
index 2ca7450..1196a9c 100644
--- a/index.html
+++ b/index.html
@@ -21,14 +21,15 @@
 				<h1>Hi.</h1>
 				<p>Welcome to one of the most boring websites on the internet.</p>
 
-				<p>Feel free to peruse any of the <em>five</em> (5) interesting things
+				<p>Feel free to peruse any of the <em>six</em> (6) interesting things
 				on this site:</p>
 				<ul>
 					<li><a href="https://scm.dairydemon.net">my software forge</a></li>
-					<li><a href='mgs/mgs.html'>this Metal Gear Solid trivia game I made</a>
-					<li><a href='statsapi/index.html'>generated documentation for MLB's Stats API</a>
-					<li><a href='eulerbooks/eulerbooks.html'>Jupyter notebooks for the first 100 Project Euler problems</a>
-					<li><a href='taoup/taoup.html'>The Art of Unix Programming by Eric S. Raymond, converted to an epub</a>
+					<li><a href='mgs/mgs.html'>this Metal Gear Solid trivia game I made</a></li>
+					<li><a href='statsapi/index.html'>generated documentation for MLB's Stats API</a></li>
+					<li><a href='eulerbooks/eulerbooks.html'>Jupyter notebooks for the first 100 Project Euler problems</a></li>
+					<li><a href='taoup/taoup.html'>The Art of Unix Programming by Eric S. Raymond, converted to an epub</a></li>
+					<li><a href="mcalc/index.html">a modular arithmetic calculator</a></li>
 				</ul>
 			</article>
 		</main>
diff --git a/mcalc b/mcalc
new file mode 160000
index 0000000..4e5e59f
--- /dev/null
+++ b/mcalc
@@ -0,0 +1 @@
+Subproject commit 4e5e59f6aa006a63bbb7f19a4c774fedc6adcdc5