diff --git a/go/gcimporter15/bexport.go b/go/gcimporter15/bexport.go
index c414c7a7..539c7a42 100644
--- a/go/gcimporter15/bexport.go
+++ b/go/gcimporter15/bexport.go
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build go1.6
-
 // Binary package export.
 // This file was derived from $GOROOT/src/cmd/compile/internal/gc/bexport.go;
 // see that file for specification of the format.
diff --git a/go/gcimporter15/bexport_test.go b/go/gcimporter15/bexport_test.go
index bc72bf64..6ab3bcb1 100644
--- a/go/gcimporter15/bexport_test.go
+++ b/go/gcimporter15/bexport_test.go
@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build go1.6
-
 package gcimporter_test
 
 import (
diff --git a/go/gcimporter15/bimport.go b/go/gcimporter15/bimport.go
index b3fe9617..e0ca8c9e 100644
--- a/go/gcimporter15/bimport.go
+++ b/go/gcimporter15/bimport.go
@@ -2,9 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build go1.6
-
-// This file is a copy of $GOROOT/src/go/internal/gcimporter/bimport.go, tagged for go1.6.
+// This file is a copy of $GOROOT/src/go/internal/gcimporter/bimport.go.
 
 package gcimporter
 
@@ -292,7 +290,7 @@ func (p *importer) obj(tag int) {
 		_ = pos
 		_ = name
 		_ = orig
-		// p.declare(types_NewAlias(pos, p.pkgList[0], name, orig))
+		// p.declare(types.NewAlias(pos, p.pkgList[0], name, orig))
 
 	default:
 		errorf("unexpected object tag %d", tag)
diff --git a/go/gcimporter15/exportdata.go b/go/gcimporter15/exportdata.go
index b4b89d65..f33dc561 100644
--- a/go/gcimporter15/exportdata.go
+++ b/go/gcimporter15/exportdata.go
@@ -2,9 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build go1.6
-
-// This file is a copy of $GOROOT/src/go/internal/gcimporter/exportdata.go, tagged for go1.6.
+// This file is a copy of $GOROOT/src/go/internal/gcimporter/exportdata.go.
 
 // This file implements FindExportData.
 
diff --git a/go/gcimporter15/gcimporter.go b/go/gcimporter15/gcimporter.go
index a0f9dfdf..48a4ef29 100644
--- a/go/gcimporter15/gcimporter.go
+++ b/go/gcimporter15/gcimporter.go
@@ -2,20 +2,14 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build go1.6
-
-// This file is a copy of $GOROOT/src/go/internal/gcimporter/gcimporter.go, tagged for go1.6,
-// and minimally adjusted to make it build.
+// This file is a copy of $GOROOT/src/go/internal/gcimporter/gcimporter.go,
+// but it also contains the original source-based importer code for Go1.6.
+// Once we stop supporting 1.6, we can remove that code.
 
 // Package gcimporter15 provides various functions for reading
 // gc-generated object files that can be used to implement the
 // Importer interface defined by the Go 1.5 standard library package.
 //
-// This package serves as a stop-gap for missing features in the
-// standard library's go/importer package, specifically customizable
-// package data lookup. This package should be deleted once that
-// functionality becomes available in the standard library.
-//
 // Deprecated: this package will be deleted in October 2017.
 // New code should use golang.org/x/tools/go/gcexportdata.
 //
diff --git a/go/gcimporter15/gcimporter_test.go b/go/gcimporter15/gcimporter_test.go
index e4e481db..3e23c560 100644
--- a/go/gcimporter15/gcimporter_test.go
+++ b/go/gcimporter15/gcimporter_test.go
@@ -2,10 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build go1.6
-
-// This file is a copy of $GOROOT/src/go/internal/gcimporter/gcimporter_test.go, tagged for go1.6,
-// and minimally adjusted to make it build with code from (std lib) internal/testenv copied.
+// This file is a copy of $GOROOT/src/go/internal/gcimporter/gcimporter_test.go,
+// adjusted to make it build with code from (std lib) internal/testenv copied.
 
 package gcimporter