diff --git a/spew/bypass.go b/spew/bypass.go
index 565bf58..96f29b6 100644
--- a/spew/bypass.go
+++ b/spew/bypass.go
@@ -15,7 +15,7 @@
 // NOTE: Due to the following build constraints, this file will only be compiled
 // when the code is not running on Google App Engine and "-tags disableunsafe"
 // is not added to the go build command line.
-// +build !appengine,!disableunsafe
+// +build !appengine,!disableunsafe,!js
 
 package spew
 
diff --git a/spew/bypasssafe.go b/spew/bypasssafe.go
index 457e412..4fd9b94 100644
--- a/spew/bypasssafe.go
+++ b/spew/bypasssafe.go
@@ -15,7 +15,7 @@
 // NOTE: Due to the following build constraints, this file will only be compiled
 // when either the code is running on Google App Engine or "-tags disableunsafe"
 // is added to the go build command line.
-// +build appengine disableunsafe
+// +build appengine disableunsafe js
 
 package spew
 
diff --git a/spew/internalunsafe_test.go b/spew/internalunsafe_test.go
index 83e070e..8c45e16 100644
--- a/spew/internalunsafe_test.go
+++ b/spew/internalunsafe_test.go
@@ -15,7 +15,7 @@
 // NOTE: Due to the following build constraints, this file will only be compiled
 // when the code is not running on Google App Engine and "-tags disableunsafe"
 // is not added to the go build command line.
-// +build !appengine,!disableunsafe
+// +build !appengine,!disableunsafe,!js
 
 /*
 This test file is part of the spew package rather than than the spew_test