diff --git a/docs/docs/CHANGELOG.md b/docs/docs/CHANGELOG.md
index 78abe7b..b33d876 100644
--- a/docs/docs/CHANGELOG.md
+++ b/docs/docs/CHANGELOG.md
@@ -24,6 +24,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Rename cookies in response to user feedback
 - Ensure cookie renaming is consistent across configuration options
 - Add Bookstack app in data
+- Ensure client JavaScript is served with Content-Type text/javascript.
 - Add `--target-host` flag/envvar to allow changing the value of the Host header in requests forwarded to the target service.
 - Bump AI-robots.txt to version 1.31
 - Add `RuntimeDirectory` to systemd unit settings so native packages can listen over unix sockets
diff --git a/internal/mimetype.go b/internal/mimetype.go
new file mode 100644
index 0000000..a0a1566
--- /dev/null
+++ b/internal/mimetype.go
@@ -0,0 +1,7 @@
+package internal
+
+import "mime"
+
+func init() {
+	mime.AddExtensionType(".mjs", "text/javascript")
+}