diff --git a/.mocharc.json b/.mocharc.json
index 216205b27..ea2ca083e 100644
--- a/.mocharc.json
+++ b/.mocharc.json
@@ -1,5 +1,5 @@
 {
-  "extension": ["ts"],
+  "extension": [".ts"],
   "spec": "./src/**/*.test.ts",
   "node-option": ["loader=esmock", "loader=node-esm-loader"],
   "require": "./mochaSetup.js"