diff --git a/src/testdir/test_cursor_func.vim b/src/testdir/test_cursor_func.vim
index d2685ed..a48db15 100644
--- a/src/testdir/test_cursor_func.vim
+++ b/src/testdir/test_cursor_func.vim
@@ -287,8 +287,9 @@
 
 " Test for the charcol() function
 func Test_charcol()
-  call assert_fails('call charcol({})', 'E731:')
-  call assert_equal(0, charcol(0))
+  call assert_fails('call charcol({})', 'E1222:')
+  call assert_fails('call charcol(".", [])', 'E1210:')
+  call assert_fails('call charcol(0)', 'E1222:')
   new
   call setline(1, ['', "01\tà4è678", 'Ⅵ', '012345678'])
 
@@ -344,6 +345,25 @@
   call assert_equal([1, 10, 2, 10, 7], g:InsertCurrentCol)
   iunmap <F3>
 
+  " Test for getting the column number in another window.
+  let winid = win_getid()
+  new
+  call win_execute(winid, 'normal 1G')
+  call assert_equal(1, charcol('.', winid))
+  call assert_equal(1, charcol('$', winid))
+  call win_execute(winid, 'normal 2G6l')
+  call assert_equal(7, charcol('.', winid))
+  call assert_equal(10, charcol('$', winid))
+
+  " calling from another tab page also works
+  tabnew
+  call assert_equal(7, charcol('.', winid))
+  call assert_equal(10, charcol('$', winid))
+  tabclose
+
+  " unknown window ID
+  call assert_equal(0, charcol('.', 10001))
+
   %bw!
 endfunc
 
diff --git a/src/testdir/test_functions.vim b/src/testdir/test_functions.vim
index 131db10..d0508ce 100644
--- a/src/testdir/test_functions.vim
+++ b/src/testdir/test_functions.vim
@@ -1484,7 +1484,8 @@
   call assert_equal(0, col([1, 100]))
   call assert_equal(0, col([1]))
   call assert_equal(0, col(test_null_list()))
-  call assert_fails('let c = col({})', 'E731:')
+  call assert_fails('let c = col({})', 'E1222:')
+  call assert_fails('let c = col(".", [])', 'E1210:')
 
   " test for getting the visual start column
   func T()
@@ -1514,6 +1515,15 @@
   call assert_equal(4, col('.'))
   set virtualedit&
 
+  " Test for getting the column number in another window
+  let winid = win_getid()
+  new
+  call win_execute(winid, 'normal 1G$')
+  call assert_equal(3, col('.', winid))
+  call win_execute(winid, 'normal 2G')
+  call assert_equal(8, col('$', winid))
+  call assert_equal(0, col('.', 5001))
+
   bw!
 endfunc
 
diff --git a/src/testdir/test_vim9_builtin.vim b/src/testdir/test_vim9_builtin.vim
index 10ae2ee..ecbfeac 100644
--- a/src/testdir/test_vim9_builtin.vim
+++ b/src/testdir/test_vim9_builtin.vim
@@ -687,6 +687,7 @@
 def Test_charcol()
   v9.CheckDefAndScriptFailure(['charcol(10)'], ['E1013: Argument 1: type mismatch, expected string but got number', 'E1222: String or List required for argument 1'])
   v9.CheckDefAndScriptFailure(['charcol({a: 10})'], ['E1013: Argument 1: type mismatch, expected string but got dict<number>', 'E1222: String or List required for argument 1'])
+  v9.CheckDefAndScriptFailure(['charcol(".", [])'], ['E1013: Argument 2: type mismatch, expected number but got list<unknown>', 'E1210: Number required for argument 2'])
   v9.CheckDefExecAndScriptFailure(['charcol("")'], 'E1209: Invalid value for a line number')
   new
   setline(1, ['abcdefgh'])
@@ -734,6 +735,7 @@
   v9.CheckDefAndScriptFailure(['col(10)'], ['E1013: Argument 1: type mismatch, expected string but got number', 'E1222: String or List required for argument 1'])
   v9.CheckDefAndScriptFailure(['col({a: 10})'], ['E1013: Argument 1: type mismatch, expected string but got dict<number>', 'E1222: String or List required for argument 1'])
   v9.CheckDefAndScriptFailure(['col(true)'], ['E1013: Argument 1: type mismatch, expected string but got bool', 'E1222: String or List required for argument 1'])
+  v9.CheckDefAndScriptFailure(['col(".", [])'], ['E1013: Argument 2: type mismatch, expected number but got list<unknown>', 'E1210: Number required for argument 2'])
   v9.CheckDefExecAndScriptFailure(['col("")'], 'E1209: Invalid value for a line number')
   bw!
 enddef
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index 5a17880..faaa915 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -53,7 +53,7 @@
       assert_equal(function('len'), Res)
 
       var RetOne: func(string): number = function('len')
-      var RetTwo: func(string): number = function('charcol')
+      var RetTwo: func(string): number = function('strlen')
       var RetThat: func = g:atrue ? RetOne : RetTwo
       assert_equal(function('len'), RetThat)