diff --git a/src/mime/type_unix.go b/src/mime/type_unix.go
index bb06a77c45..6549c0f5e9 100644
--- a/src/mime/type_unix.go
+++ b/src/mime/type_unix.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build darwin dragonfly freebsd linux nacl netbsd openbsd solaris
+// +build darwin dragonfly freebsd js,wasm linux nacl netbsd openbsd solaris
 
 package mime