diff --git a/.markdownlint.json b/.markdownlint.json
index 3536479a..c9b4bb5c 100644
--- a/.markdownlint.json
+++ b/.markdownlint.json
@@ -6,6 +6,8 @@
       "ts",
       "javascript",
       "typescript",
+      "gjs",
+      "gts",
       "bash",
       "shell",
       "handlebars",
diff --git a/config/environment.js b/config/environment.js
index 0c61c087..9d4311b6 100644
--- a/config/environment.js
+++ b/config/environment.js
@@ -36,6 +36,8 @@ module.exports = function (environment) {
       languages: [
         'javascript',
         'typescript',
+        'glimmer-js',
+        'glimmer-ts',
         'handlebars',
         'json',
         'diff',