diff --git a/src/proto/vim9compile.pro b/src/proto/vim9compile.pro
index 03862a2..fb37923 100644
--- a/src/proto/vim9compile.pro
+++ b/src/proto/vim9compile.pro
@@ -3,6 +3,7 @@
 void clear_type_list(garray_T *gap);
 type_T *typval2type(typval_T *tv);
 int check_type(type_T *expected, type_T *actual, int give_msg);
+int check_argtype(type_T *expected, typval_T *actual_tv);
 int check_compare_types(exptype_T type, typval_T *tv1, typval_T *tv2);
 char_u *skip_type(char_u *start);
 type_T *parse_type(char_u **arg, garray_T *type_gap);
diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index 9b61821..6d83ddc 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -407,6 +407,17 @@
   delete('Xcall_decl.vim')
 enddef
 
+def Test_vim9script_call_fail_type()
+  let lines =<< trim END
+    vim9script
+    def MyFunc(arg: string)
+      echo arg
+    enddef
+    MyFunc(1234)
+  END
+  CheckScriptFailure(lines, 'E1013: type mismatch, expected string but got number')
+enddef
+
 def Test_vim9script_call_fail_const()
   let lines =<< trim END
     vim9script
diff --git a/src/version.c b/src/version.c
index 2d0fbb2..2e8f423 100644
--- a/src/version.c
+++ b/src/version.c
@@ -755,6 +755,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    1242,
+/**/
     1241,
 /**/
     1240,
diff --git a/src/vim9compile.c b/src/vim9compile.c
index 634706b..81d5324 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -560,6 +560,50 @@
     return ret;
 }
 
+/*
+ * Return FAIl if "expected" and "actual" don't match.
+ * TODO: better type comparison
+ */
+    int
+check_argtype(type_T *expected, typval_T *actual_tv)
+{
+    type_T  actual;
+    type_T  member;
+
+    // TODO: should should be done with more levels
+    CLEAR_FIELD(actual);
+    actual.tt_type = actual_tv->v_type;
+    if (actual_tv->v_type == VAR_LIST
+	    && actual_tv->vval.v_list != NULL
+	    && actual_tv->vval.v_list->lv_first != NULL)
+    {
+	// Use the type of the first member, it is the most specific.
+	CLEAR_FIELD(member);
+	member.tt_type = actual_tv->vval.v_list->lv_first->li_tv.v_type;
+	member.tt_member = &t_any;
+	actual.tt_member = &member;
+    }
+    else if (actual_tv->v_type == VAR_DICT
+	    && actual_tv->vval.v_dict != NULL
+	    && actual_tv->vval.v_dict->dv_hashtab.ht_used > 0)
+    {
+	dict_iterator_T iter;
+	typval_T	*value;
+
+	// Use the type of the first value, it is the most specific.
+	dict_iterate_start(actual_tv, &iter);
+	dict_iterate_next(&iter, &value);
+	CLEAR_FIELD(member);
+	member.tt_type = value->v_type;
+	member.tt_member = &t_any;
+	actual.tt_member = &member;
+    }
+    else
+	actual.tt_member = &t_any;
+    return check_type(expected, &actual, TRUE);
+}
+
+
 /////////////////////////////////////////////////////////////////////
 // Following generate_ functions expect the caller to call ga_grow().
 
diff --git a/src/vim9execute.c b/src/vim9execute.c
index 9f037a3..7ba76e5 100644
--- a/src/vim9execute.c
+++ b/src/vim9execute.c
@@ -737,6 +737,9 @@
     // Put arguments on the stack.
     for (idx = 0; idx < argc; ++idx)
     {
+	if (ufunc->uf_arg_types != NULL && idx < ufunc->uf_args.ga_len
+		&& check_argtype(ufunc->uf_arg_types[idx], &argv[idx]) == FAIL)
+	    goto failed_early;
 	copy_tv(&argv[idx], STACK_TV_BOT(0));
 	++ectx.ec_stack.ga_len;
     }