diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index e15199b..fd9057d 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -2077,6 +2077,13 @@
   set encoding=utf-8
 endfunc
 
+func Test_charclass()
+  call assert_equal(0, charclass(' '))
+  call assert_equal(1, charclass('.'))
+  call assert_equal(2, charclass('x'))
+  call assert_equal(3, charclass("\u203c"))
+endfunc
+
 func Test_eventhandler()
   call assert_equal(0, eventhandler())
 endfunc