diff --git a/.gitmodules b/.gitmodules
index 04020c84d1..09e695b83c 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -16,3 +16,6 @@
 [submodule "src/monad_app_base"]
 	path = src/monad_app_base
 	url = https://msostc.visualstudio.com/DefaultCollection/PS/_git/monad_app_base
+[submodule "ext-src/pester"]
+	path = ext-src/pester
+	url = https://github.com/pester/Pester.git
diff --git a/ext-src/pester b/ext-src/pester
new file mode 160000
index 0000000000..b26b3cc936
--- /dev/null
+++ b/ext-src/pester
@@ -0,0 +1 @@
+Subproject commit b26b3cc93644640331cf33b4ca9b7f2012e5adca