diff --git a/vlib/v/builder/builder.v b/vlib/v/builder/builder.v
index ff2e92f2fa..e1ac8b7f8b 100644
--- a/vlib/v/builder/builder.v
+++ b/vlib/v/builder/builder.v
@@ -60,6 +60,10 @@ pub fn (mut b Builder) parse_imports() {
 		ast_file := b.parsed_files[i]
 		for _, imp in ast_file.imports {
 			mod := imp.mod
+			if mod == 'builtin' {
+				verror('cannot import module "$mod"')
+				break
+			}
 			if mod in done_imports {
 				continue
 			}