diff --git a/src/proto/userfunc.pro b/src/proto/userfunc.pro
index 7b4129b..e393c04 100644
--- a/src/proto/userfunc.pro
+++ b/src/proto/userfunc.pro
@@ -7,7 +7,7 @@
 int get_lambda_tv(char_u **arg, typval_T *rettv, int types_optional, evalarg_T *evalarg);
 char_u *deref_func_name(char_u *name, int *lenp, partial_T **partialp, type_T **type, int no_autoload, int new_function, int *found_var);
 void emsg_funcname(char *ermsg, char_u *name);
-int get_func_arguments(char_u **arg, evalarg_T *evalarg, int partial_argc, typval_T *argvars, int *argcount);
+int get_func_arguments(char_u **arg, evalarg_T *evalarg, int partial_argc, typval_T *argvars, int *argcount, int is_builtin);
 int get_func_tv(char_u *name, int len, typval_T *rettv, char_u **arg, evalarg_T *evalarg, funcexe_T *funcexe);
 char_u *fname_trans_sid(char_u *name, char_u *fname_buf, char_u **tofree, funcerror_T *error);
 void func_name_with_sid(char_u *name, int sid, char_u *buffer);
diff --git a/src/testdir/test_vim9_assign.vim b/src/testdir/test_vim9_assign.vim
index 38504f1..d582000 100644
--- a/src/testdir/test_vim9_assign.vim
+++ b/src/testdir/test_vim9_assign.vim
@@ -3197,7 +3197,7 @@
       assert_fails('IntArg(j)', 'E1013: Argument 1: type mismatch, expected number but got job')
       assert_fails('IntArg(ch)', 'E1013: Argument 1: type mismatch, expected number but got channel')
     endif
-    assert_fails('IntArg(A)', 'E1013: Argument 1: type mismatch, expected number but got class<A>')
+    assert_fails('IntArg(A)', 'E1405: Class "A" cannot be used as a value')
     assert_fails('IntArg(o)', 'E1013: Argument 1: type mismatch, expected number but got object<A>')
 
     # Passing a number to functions accepting different argument types
@@ -3262,7 +3262,7 @@
     v9.CheckSourceFailure(lines, 'E1013: Argument 1: type mismatch, expected number but got channel', 2)
   endif
   lines = pre_lines + ['IntArg(A)'] + post_lines
-  v9.CheckSourceFailure(lines, 'E1013: Argument 1: type mismatch, expected number but got class<A>', 1)
+  v9.CheckSourceFailure(lines, 'E1405: Class "A" cannot be used as a value', 1)
   lines = pre_lines + ['var o: A = A.new()', 'IntArg(o)'] + post_lines
   v9.CheckSourceFailure(lines, 'E1013: Argument 1: type mismatch, expected number but got object<A>', 2)
 enddef
diff --git a/src/testdir/test_vim9_class.vim b/src/testdir/test_vim9_class.vim
index 5a9b0f8..6f9723d 100644
--- a/src/testdir/test_vim9_class.vim
+++ b/src/testdir/test_vim9_class.vim
@@ -4149,7 +4149,7 @@
 
     Lock2(C)
   END
-  v9.CheckSourceSuccess(lines)
+  v9.CheckSourceFailure(lines, 'E1405: Class "C" cannot be used as a value')
 
   # Lock an object.
   lines =<< trim END
diff --git a/src/testdir/test_vim9_typealias.vim b/src/testdir/test_vim9_typealias.vim
index 11aa47a..8843cb5 100644
--- a/src/testdir/test_vim9_typealias.vim
+++ b/src/testdir/test_vim9_typealias.vim
@@ -546,4 +546,238 @@
   v9.CheckScriptSuccess(lines)
 enddef
 
+" Test for typealias as function arg and return value
+def Test_type_as_func_argument_or_return_value()
+  # check typealias as arg, function call in script level
+  var lines =<< trim END
+    vim9script
+    type A = number
+    def Foo(arg: any)
+    enddef
+    Foo(A)
+  END
+  v9.CheckScriptFailure(lines, 'E1403: Type alias "A" cannot be used as a value', 5)
+
+  # check typealias as function return, function call in script level
+  lines =<< trim END
+    vim9script
+    type A = number
+    def Foo(): any
+      return A
+    enddef
+    Foo()
+  END
+  v9.CheckScriptFailure(lines, 'E1407: Cannot use a Typealias as a variable or value', 1)
+
+  # check typealias as arg, function call in :def
+  lines =<< trim END
+    vim9script
+    type A = number
+    def Foo(arg: any)
+    enddef
+    def F()
+      Foo(A)
+    enddef
+    F()
+  END
+  v9.CheckScriptFailure(lines, 'E1407: Cannot use a Typealias as a variable or value', 1)
+
+  # check typealias as function return, function call in :def
+  lines =<< trim END
+    vim9script
+    type A = number
+    def Foo(): any
+      return A
+    enddef
+    def F()
+      Foo()
+    enddef
+    F()
+  END
+  v9.CheckScriptFailure(lines, 'E1407: Cannot use a Typealias as a variable or value', 1)
+
+  # check funcref using typealias as arg at script level
+  lines =<< trim END
+    vim9script
+    type A = number
+    def F(arg: any)
+      echo typename(arg)
+    enddef
+    var Fref: func(any)
+    Fref = F
+
+    Fref(A)
+  END
+  v9.CheckScriptFailure(lines, 'E1403: Type alias "A" cannot be used as a value', 9)
+
+  # check funcref using typealias as arg in :def
+  lines =<< trim END
+    vim9script
+    type A = number
+    def F(arg: any)
+      echo typename(arg)
+    enddef
+    var Fref: func(any)
+    Fref = F
+
+    def G()
+      Fref(A)
+    enddef
+    G()
+  END
+  v9.CheckScriptFailure(lines, 'E1407: Cannot use a Typealias as a variable or value', 1)
+
+  # check funcref using typealias as return
+  lines =<< trim END
+    vim9script
+    type A = number
+    def F(): any
+      return A
+    enddef
+    var Fref: func(): any
+    Fref = F
+
+    Fref()
+  END
+  v9.CheckScriptFailure(lines, 'E1407: Cannot use a Typealias as a variable or value', 1)
+
+  # check defered function using typealias as arg
+  lines =<< trim END
+    vim9script
+    type A = number
+    def F(arg: any)
+    enddef
+    def G()
+      defer F(A)
+    enddef
+    G()
+  END
+  v9.CheckScriptFailure(lines, 'E1407: Cannot use a Typealias as a variable or value', 1)
+enddef
+
+" Test for class typealias as function arg and return value
+def Test_class_as_func_argument_or_return_value()
+  # check class typealias as arg, function call in script level
+  var lines =<< trim END
+    vim9script
+    class C
+    endclass
+    type A = C
+    def Foo(arg: any)
+    enddef
+    Foo(A)
+  END
+  v9.CheckScriptFailure(lines, 'E1405: Class "C" cannot be used as a value', 7)
+
+  # check class typealias as function return, function call in script level
+  lines =<< trim END
+    vim9script
+    class C
+    endclass
+    type A = C
+    def Foo(): any
+      return A
+    enddef
+    Foo()
+  END
+  v9.CheckScriptFailure(lines, 'E1405: Class "C" cannot be used as a value', 1)
+
+  # check class typealias as arg, function call in :def
+  lines =<< trim END
+    vim9script
+    class C
+    endclass
+    type A = C
+    def Foo(arg: any)
+    enddef
+    def F()
+      Foo(A)
+    enddef
+    F()
+  END
+  v9.CheckScriptFailure(lines, 'E1405: Class "C" cannot be used as a value', 1)
+
+  # check class typealias as function return, function call in :def
+  lines =<< trim END
+    vim9script
+    class C
+    endclass
+    type A = C
+    def Foo(): any
+      return A
+    enddef
+    def F()
+      Foo()
+    enddef
+    F()
+  END
+  v9.CheckScriptFailure(lines, 'E1405: Class "C" cannot be used as a value', 1)
+
+  # check funcref using class typealias as arg at script level
+  lines =<< trim END
+    vim9script
+    class C
+    endclass
+    type A = C
+    def F(arg: any)
+      echo typename(arg)
+    enddef
+    var Fref: func(any)
+    Fref = F
+
+    Fref(A)
+  END
+  v9.CheckScriptFailure(lines, 'E1405: Class "C" cannot be used as a value', 11)
+
+  # check funcref using class typealias as arg in :def
+  lines =<< trim END
+    vim9script
+    class C
+    endclass
+    type A = C
+    def F(arg: any)
+      echo typename(arg)
+    enddef
+    var Fref: func(any)
+    Fref = F
+
+    def G()
+      Fref(A)
+    enddef
+    G()
+  END
+  v9.CheckScriptFailure(lines, 'E1405: Class "C" cannot be used as a value', 1)
+
+  # check funcref using class typealias as return
+  lines =<< trim END
+    vim9script
+    class C
+    endclass
+    type A = C
+    def F(): any
+      return A
+    enddef
+    var Fref: func(): any
+    Fref = F
+
+    Fref()
+  END
+  v9.CheckScriptFailure(lines, 'E1405: Class "C" cannot be used as a value', 1)
+
+  # check defered function using class typealias as arg
+  lines =<< trim END
+    vim9script
+    class C
+    endclass
+    type A = C
+    def F(arg: any)
+    enddef
+    def G()
+      defer F(A)
+    enddef
+    G()
+  END
+  v9.CheckScriptFailure(lines, 'E1405: Class "C" cannot be used as a value', 1)
+enddef
+
 " vim: ts=8 sw=2 sts=2 expandtab tw=80 fdm=marker
diff --git a/src/userfunc.c b/src/userfunc.c
index 410658b..1580a37 100644
--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -1905,7 +1905,8 @@
 	evalarg_T   *evalarg,
 	int	    partial_argc,
 	typval_T    *argvars,
-	int	    *argcount)
+	int	    *argcount,
+	int	    is_builtin)
 {
     char_u	*argp = *arg;
     int		ret = OK;
@@ -1920,12 +1921,20 @@
 
 	if (*argp == ')' || *argp == ',' || *argp == NUL)
 	    break;
-	if (eval1(&argp, &argvars[*argcount], evalarg) == FAIL)
+
+	int arg_idx = *argcount;
+	if (eval1(&argp, &argvars[arg_idx], evalarg) == FAIL)
 	{
 	    ret = FAIL;
 	    break;
 	}
 	++*argcount;
+	if (!is_builtin && check_typval_is_value(&argvars[arg_idx]) == FAIL)
+	{
+	    ret = FAIL;
+	    break;
+	}
+
 	// The comma should come right after the argument, but this wasn't
 	// checked previously, thus only enforce it in Vim9 script.
 	if (vim9script)
@@ -1985,7 +1994,7 @@
     argp = *arg;
     ret = get_func_arguments(&argp, evalarg,
 	    (funcexe->fe_partial == NULL ? 0 : funcexe->fe_partial->pt_argc),
-							   argvars, &argcount);
+			       argvars, &argcount, builtin_function(name, -1));
 
     if (ret == OK)
     {
@@ -6125,8 +6134,9 @@
 		copy_tv(&partial->pt_argv[i], &argvars[i]);
 	}
     }
+    int is_builtin = builtin_function(name, -1);
     r = get_func_arguments(arg, evalarg, FALSE,
-					    argvars + partial_argc, &argcount);
+				argvars + partial_argc, &argcount, is_builtin);
     argcount += partial_argc;
 
     if (r == OK)
@@ -6136,7 +6146,7 @@
 	    // Check that the arguments are OK for the types of the funcref.
 	    r = check_argument_types(type, argvars, argcount, NULL, name);
 	}
-	else if (builtin_function(name, -1))
+	else if (is_builtin)
 	{
 	    int idx = find_internal_func(name);
 
diff --git a/src/version.c b/src/version.c
index a4b4edf..6424f7f 100644
--- a/src/version.c
+++ b/src/version.c
@@ -705,6 +705,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    2164,
+/**/
     2163,
 /**/
     2162,
diff --git a/src/vim9class.c b/src/vim9class.c
index 2c5e1df..b19f8c9 100644
--- a/src/vim9class.c
+++ b/src/vim9class.c
@@ -2342,7 +2342,7 @@
     }
 
     char_u *argp = name_end;
-    int ret = get_func_arguments(&argp, evalarg, 0, argvars, &argcount);
+    int ret = get_func_arguments(&argp, evalarg, 0, argvars, &argcount, FALSE);
     if (ret == FAIL)
 	return FAIL;
 
diff --git a/src/vim9cmds.c b/src/vim9cmds.c
index 92605cf..392bab4 100644
--- a/src/vim9cmds.c
+++ b/src/vim9cmds.c
@@ -2661,6 +2661,8 @@
 	    // for an inline function without a specified return type.  Set the
 	    // return type here.
 	    stack_type = get_type_on_stack(cctx, 0);
+	    if (check_type_is_value(stack_type) == FAIL)
+		return NULL;
 	    if ((check_return_type && (cctx->ctx_ufunc->uf_ret_type == NULL
 				|| cctx->ctx_ufunc->uf_ret_type == &t_unknown))
 		    || (!check_return_type
diff --git a/src/vim9execute.c b/src/vim9execute.c
index d357fc4..882b13c 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -398,6 +398,9 @@
 	if (argv[i].v_type == VAR_SPECIAL
 		&& argv[i].vval.v_number == VVAL_NONE)
 	    continue;
+	// only pass values to user functions, never types
+	if (check_typval_is_value(&argv[i]) == FAIL)
+	    return FAIL;
 
 	if (i < ufunc->uf_args.ga_len && ufunc->uf_arg_types != NULL)
 	    type = ufunc->uf_arg_types[i];
@@ -4462,6 +4465,12 @@
 		    garray_T	*trystack = &ectx->ec_trystack;
 		    trycmd_T    *trycmd = NULL;
 
+		    ///////////////////////////////////////////////////
+		    // TODO: If FAIL, line number in output not correct
+		    ///////////////////////////////////////////////////
+		    if (check_typval_is_value(STACK_TV_BOT(-1)) == FAIL)
+			goto theend;
+
 		    if (trystack->ga_len > 0)
 			trycmd = ((trycmd_T *)trystack->ga_data)
 							+ trystack->ga_len - 1;
diff --git a/src/vim9instr.c b/src/vim9instr.c
index 12c83df..b7cad76 100644
--- a/src/vim9instr.c
+++ b/src/vim9instr.c
@@ -1821,6 +1821,8 @@
 	    type_T *actual;
 
 	    actual = get_type_on_stack(cctx, argcount - i - 1);
+	    if (check_type_is_value(actual) == FAIL)
+		return FAIL;
 	    if (actual->tt_type == VAR_SPECIAL
 			      && i >= regular_args - ufunc->uf_def_args.ga_len)
 	    {
@@ -1960,6 +1962,8 @@
 		type_T	*actual = get_type_on_stack(cctx, -1 - offset);
 		type_T	*expected;
 
+		if (check_type_is_value(actual) == FAIL)
+		    return FAIL;
 		if (varargs && i >= type->tt_argcount - 1)
 		{
 		    expected = type->tt_args[type->tt_argcount - 1];