diff --git a/.gitmodules b/.gitmodules
index d4ffeb4b3..b76996fce 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -4,3 +4,6 @@
 [submodule "ext/googletest"]
 	path = ext/googletest
 	url = https://github.com/google/googletest.git
+[submodule "ext/sundials"]
+	path = ext/sundials
+	url = https://github.com/Cantera/sundials-mirror
diff --git a/ext/sundials b/ext/sundials
new file mode 160000
index 000000000..b69354ec7
--- /dev/null
+++ b/ext/sundials
@@ -0,0 +1 @@
+Subproject commit b69354ec776e38e08367fd89880b43459fda3d92