diff --git a/blake2s/blake2s_386.go b/blake2s/blake2s_386.go
index 3ed0c8c..8575080 100644
--- a/blake2s/blake2s_386.go
+++ b/blake2s/blake2s_386.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 386, !gccgo, !appengine
+// +build 386,!gccgo,!appengine
 
 package blake2s
 
diff --git a/blake2s/blake2s_386.s b/blake2s/blake2s_386.s
index 0154863..0bb65c7 100644
--- a/blake2s/blake2s_386.s
+++ b/blake2s/blake2s_386.s
@@ -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 386, !gccgo, !appengine
+// +build 386,!gccgo,!appengine
 
 #include "textflag.h"
 
diff --git a/blake2s/blake2s_amd64.go b/blake2s/blake2s_amd64.go
index c88f330..43a7625 100644
--- a/blake2s/blake2s_amd64.go
+++ b/blake2s/blake2s_amd64.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 amd64, !gccgo, !appengine
+// +build amd64,!gccgo,!appengine
 
 package blake2s
 
diff --git a/blake2s/blake2s_amd64.s b/blake2s/blake2s_amd64.s
index 594a3af..6cdf5a9 100644
--- a/blake2s/blake2s_amd64.s
+++ b/blake2s/blake2s_amd64.s
@@ -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 amd64, !gccgo, !appengine
+// +build amd64,!gccgo,!appengine
 
 #include "textflag.h"
 
diff --git a/blake2s/blake2s_ref.go b/blake2s/blake2s_ref.go
index 9ce99f2..7e54230 100644
--- a/blake2s/blake2s_ref.go
+++ b/blake2s/blake2s_ref.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 !amd64,!386, gccgo, appengine
+// +build !amd64,!386 gccgo appengine
 
 package blake2s