diff --git a/build/build.go b/build/build.go
index 2c835ccf0..e82e8052e 100644
--- a/build/build.go
+++ b/build/build.go
@@ -90,19 +90,6 @@ func Import(path string, mode build.ImportMode, installSuffix string, buildTags
 	return xctx.Import(path, wd, mode)
 }
 
-// excludeExecutable excludes all executable implementation .go files.
-// They have "executable_" prefix.
-func excludeExecutable(goFiles []string) []string {
-	var s []string
-	for _, f := range goFiles {
-		if strings.HasPrefix(f, "executable_") {
-			continue
-		}
-		s = append(s, f)
-	}
-	return s
-}
-
 // exclude returns files, excluding specified files.
 func exclude(files []string, exclude ...string) []string {
 	var s []string
@@ -118,12 +105,6 @@ Outer:
 	return s
 }
 
-func include(files []string, includes ...string) []string {
-	files = exclude(files, includes...) // Ensure there won't be duplicates.
-	files = append(files, includes...)
-	return files
-}
-
 // ImportDir is like Import but processes the Go package found in the named
 // directory.
 func ImportDir(dir string, mode build.ImportMode, installSuffix string, buildTags []string) (*PackageData, error) {
diff --git a/build/fsutil.go b/build/fsutil.go
index cee763f14..4864833d4 100644
--- a/build/fsutil.go
+++ b/build/fsutil.go
@@ -2,7 +2,6 @@ package build
 
 import (
 	"fmt"
-	"os"
 	"path/filepath"
 )
 
@@ -13,16 +12,3 @@ func mustAbs(p string) string {
 	}
 	return a
 }
-
-// makeWritable attempts to make the given path writable by its owner.
-func makeWritable(path string) error {
-	info, err := os.Stat(path)
-	if err != nil {
-		return err
-	}
-	err = os.Chmod(path, info.Mode()|0700)
-	if err != nil {
-		return err
-	}
-	return nil
-}