diff --git a/credentials/alts/alts_test.go b/credentials/alts/alts_test.go
index 616666969..ed13ee447 100644
--- a/credentials/alts/alts_test.go
+++ b/credentials/alts/alts_test.go
@@ -1,3 +1,5 @@
+// +build linux,windows
+
 /*
  *
  * Copyright 2018 gRPC authors.
diff --git a/credentials/alts/utils_test.go b/credentials/alts/utils_test.go
index 7c84c3bc9..d33f189ee 100644
--- a/credentials/alts/utils_test.go
+++ b/credentials/alts/utils_test.go
@@ -1,3 +1,5 @@
+// +build linux,windows
+
 /*
  *
  * Copyright 2018 gRPC authors.