diff --git a/src/testdir/test_json.vim b/src/testdir/test_json.vim
index e16a7f0..8f85a58 100644
--- a/src/testdir/test_json.vim
+++ b/src/testdir/test_json.vim
@@ -176,6 +176,10 @@
 
   call assert_fails('call json_decode("{{}:42}")', "E474:")
   call assert_fails('call json_decode("{[]:42}")', "E474:")
+
+  call assert_fails('call json_decode("\"\\u111Z\"")', 'E474:')
+  call assert_equal('[😂]', json_decode('"[\uD83D\uDE02]"'))
+  call assert_equal('a😂b', json_decode('"a\uD83D\uDE02b"'))
 endfunc
 
 let s:jsl5 = '[7,,,]'