diff --git a/poly1305/sum_arm.s b/poly1305/sum_arm.s
index c09f182..6742dfb 100644
--- a/poly1305/sum_arm.s
+++ b/poly1305/sum_arm.s
@@ -2,13 +2,13 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build arm,!gccgo,!appengine,!nacl
+
 #include "textflag.h"
 
 // This code was translated into a form compatible with 5a from the public
 // domain source by Andrew Moon: github.com/floodyberry/poly1305-opt/blob/master/app/extensions/poly1305.
 
-// +build arm,!gccgo,!appengine,!nacl
-
 DATA poly1305_init_constants_armv6<>+0x00(SB)/4, $0x3ffffff
 DATA poly1305_init_constants_armv6<>+0x04(SB)/4, $0x3ffff03
 DATA poly1305_init_constants_armv6<>+0x08(SB)/4, $0x3ffc0ff
diff --git a/poly1305/sum_ref.go b/poly1305/sum_ref.go
index 5d25a56..908aae0 100644
--- a/poly1305/sum_ref.go
+++ b/poly1305/sum_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,!arm gccgo appengine !go1.7
+// +build !amd64,!arm gccgo appengine nacl !go1.7
 
 package poly1305