diff --git a/nixd/tools/nixd/test/utf16.md b/nixd/tools/nixd/test/utf16.md
new file mode 100644
index 000000000..5e2e54599
--- /dev/null
+++ b/nixd/tools/nixd/test/utf16.md
@@ -0,0 +1,52 @@
+# RUN: nixd --lit-test < %s | FileCheck %s
+
+<-- initialize(0)
+
+```json
+{
+   "jsonrpc":"2.0",
+   "id":0,
+   "method":"initialize",
+   "params":{
+      "processId":123,
+      "rootPath":"",
+      "capabilities":{
+      },
+      "trace":"off"
+   }
+}
+```
+
+```json
+{
+   "jsonrpc":"2.0",
+   "method":"textDocument/didOpen",
+   "params":{
+      "textDocument":{
+         "uri":"file:///basic.nix",
+         "languageId":"nix",
+         "version":1,
+         "text":"{ a = 1; 测试文本 }"
+      }
+   }
+}
+```
+
+```
+     CHECK:  "code": "parse-unexpected",
+CHECK-NEXT:  "message": "unexpected text (fix available)",
+CHECK-NEXT:  "range": {
+CHECK-NEXT:    "end": {
+CHECK-NEXT:      "character": 13,
+CHECK-NEXT:      "line": 0
+CHECK-NEXT:    },
+CHECK-NEXT:    "start": {
+CHECK-NEXT:      "character": 9,
+CHECK-NEXT:      "line": 0
+CHECK-NEXT:    }
+CHECK-NEXT:  },
+```
+
+```json
+{"jsonrpc":"2.0","method":"exit"}
+```