diff --git a/src/testdir/test_vim9_func.vim b/src/testdir/test_vim9_func.vim
index 558f23c..6f9aa0c 100644
--- a/src/testdir/test_vim9_func.vim
+++ b/src/testdir/test_vim9_func.vim
@@ -128,6 +128,7 @@
   assert_equal('one,foo', MyDefVarargs('one'))
   assert_equal('one,two', MyDefVarargs('one', 'two'))
   assert_equal('one,two,three', MyDefVarargs('one', 'two', 'three'))
+  call CheckDefFailure(['MyDefVarargs("one", 22)'], 'E1013: argument 2: type mismatch, expected string but got number')
 enddef
 
 " Only varargs
diff --git a/src/userfunc.c b/src/userfunc.c
index 69a57c2..316eac6 100644
--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -3045,8 +3045,8 @@
 		{
 		    p = ((char_u **)argtypes.ga_data)[i];
 		    if (p == NULL)
-			// todo: get type from default value
-			type = &t_any;
+			// will get the type from the default value
+			type = &t_unknown;
 		    else
 			type = parse_type(&p, &fp->uf_type_list);
 		    if (type == NULL)
diff --git a/src/version.c b/src/version.c
index 3518aec..a3c54cb 100644
--- a/src/version.c
+++ b/src/version.c
@@ -739,6 +739,8 @@
 static int included_patches[] =
 {   /* Add new patch number below this line */
 /**/
+    529,
+/**/
     528,
 /**/
     527,
diff --git a/src/vim9compile.c b/src/vim9compile.c
index fb0adb3..a8a7647 100644
--- a/src/vim9compile.c
+++ b/src/vim9compile.c
@@ -5548,6 +5548,7 @@
     if (ufunc->uf_def_args.ga_len > 0)
     {
 	int	count = ufunc->uf_def_args.ga_len;
+	int	first_def_arg = ufunc->uf_args.ga_len - count;
 	int	i;
 	char_u	*arg;
 	int	off = STACK_FRAME_SIZE + (ufunc->uf_va_name != NULL ? 1 : 0);
@@ -5561,11 +5562,30 @@
 	    goto erret;
 	for (i = 0; i < count; ++i)
 	{
+	    garray_T	*stack = &cctx.ctx_type_stack;
+	    type_T	*val_type;
+	    int		arg_idx = first_def_arg + i;
+
 	    ufunc->uf_def_arg_idx[i] = instr->ga_len;
 	    arg = ((char_u **)(ufunc->uf_def_args.ga_data))[i];
-	    if (compile_expr1(&arg, &cctx) == FAIL
-		    || generate_STORE(&cctx, ISN_STORE,
-						i - count - off, NULL) == FAIL)
+	    if (compile_expr1(&arg, &cctx) == FAIL)
+		goto erret;
+
+	    // If no type specified use the type of the default value.
+	    // Otherwise check that the default value type matches the
+	    // specified type.
+	    val_type = ((type_T **)stack->ga_data)[stack->ga_len - 1];
+	    if (ufunc->uf_arg_types[arg_idx] == &t_unknown)
+		ufunc->uf_arg_types[arg_idx] = val_type;
+	    else if (check_type(ufunc->uf_arg_types[i], val_type, FALSE)
+								       == FAIL)
+	    {
+		arg_type_mismatch(ufunc->uf_arg_types[arg_idx], val_type,
+								  arg_idx + 1);
+		goto erret;
+	    }
+
+	    if (generate_STORE(&cctx, ISN_STORE, i - count - off, NULL) == FAIL)
 		goto erret;
 	}