diff --git a/src/cmd/godoc/codewalk.go b/src/cmd/godoc/codewalk.go
index 214fc5644e8..fb5f27596e9 100644
--- a/src/cmd/godoc/codewalk.go
+++ b/src/cmd/godoc/codewalk.go
@@ -129,7 +129,7 @@ func loadCodewalk(filename string) (*Codewalk, os.Error) {
 			i = len(st.Src)
 		}
 		filename := st.Src[0:i]
-		data, err := fs.ReadFile(absolutePath(filename, *goroot))
+		data, err := ReadFile(fs, absolutePath(filename, *goroot))
 		if err != nil {
 			st.Err = err
 			continue
@@ -208,7 +208,7 @@ func codewalkDir(w http.ResponseWriter, r *http.Request, relpath, abspath string
 // the usual godoc HTML wrapper.
 func codewalkFileprint(w http.ResponseWriter, r *http.Request, f string) {
 	abspath := absolutePath(f, *goroot)
-	data, err := fs.ReadFile(abspath)
+	data, err := ReadFile(fs, abspath)
 	if err != nil {
 		log.Print(err)
 		serveError(w, r, f, err)
diff --git a/src/cmd/godoc/filesystem.go b/src/cmd/godoc/filesystem.go
index a68c085927f..011977af904 100644
--- a/src/cmd/godoc/filesystem.go
+++ b/src/cmd/godoc/filesystem.go
@@ -31,7 +31,16 @@ type FileSystem interface {
 	Lstat(path string) (FileInfo, os.Error)
 	Stat(path string) (FileInfo, os.Error)
 	ReadDir(path string) ([]FileInfo, os.Error)
-	ReadFile(path string) ([]byte, os.Error)
+}
+
+// ReadFile reads the file named by path from fs and returns the contents.
+func ReadFile(fs FileSystem, path string) ([]byte, os.Error) {
+	rc, err := fs.Open(path)
+	if err != nil {
+		return nil, err
+	}
+	defer rc.Close()
+	return ioutil.ReadAll(rc)
 }
 
 // ----------------------------------------------------------------------------
@@ -98,7 +107,3 @@ func (osFS) ReadDir(path string) ([]FileInfo, os.Error) {
 	}
 	return l1, nil
 }
-
-func (osFS) ReadFile(path string) ([]byte, os.Error) {
-	return ioutil.ReadFile(path)
-}
diff --git a/src/cmd/godoc/godoc.go b/src/cmd/godoc/godoc.go
index c817dbe6acf..3bf721bcc06 100644
--- a/src/cmd/godoc/godoc.go
+++ b/src/cmd/godoc/godoc.go
@@ -149,7 +149,7 @@ func getPathFilter() func(string) bool {
 // readDirList reads a file containing a newline-separated list
 // of directory paths and returns the list of paths.
 func readDirList(filename string) ([]string, os.Error) {
-	contents, err := fs.ReadFile(filename)
+	contents, err := ReadFile(fs, filename)
 	if err != nil {
 		return nil, err
 	}
@@ -546,7 +546,7 @@ func readTemplate(name string) *template.Template {
 
 	// use underlying file system fs to read the template file
 	// (cannot use template ParseFile functions directly)
-	data, err := fs.ReadFile(path)
+	data, err := ReadFile(fs, path)
 	if err != nil {
 		log.Fatal("readTemplate: ", err)
 	}
@@ -636,7 +636,7 @@ func extractString(src []byte, rx *regexp.Regexp) (s string) {
 
 func serveHTMLDoc(w http.ResponseWriter, r *http.Request, abspath, relpath string) {
 	// get HTML body contents
-	src, err := fs.ReadFile(abspath)
+	src, err := ReadFile(fs, abspath)
 	if err != nil {
 		log.Printf("ReadFile: %s", err)
 		serveError(w, r, relpath, err)
@@ -685,7 +685,7 @@ func redirect(w http.ResponseWriter, r *http.Request) (redirected bool) {
 }
 
 func serveTextFile(w http.ResponseWriter, r *http.Request, abspath, relpath, title string) {
-	src, err := fs.ReadFile(abspath)
+	src, err := ReadFile(fs, abspath)
 	if err != nil {
 		log.Printf("ReadFile: %s", err)
 		serveError(w, r, relpath, err)
@@ -837,7 +837,7 @@ func fsReadDir(dir string) ([]*os.FileInfo, os.Error) {
 // fsReadFile implements ReadFile for the go/build package.
 func fsReadFile(dir, name string) (path string, data []byte, err os.Error) {
 	path = filepath.Join(dir, name)
-	data, err = fs.ReadFile(path)
+	data, err = ReadFile(fs, path)
 	return
 }
 
diff --git a/src/cmd/godoc/parser.go b/src/cmd/godoc/parser.go
index cc1780a4b5c..a2920539f29 100644
--- a/src/cmd/godoc/parser.go
+++ b/src/cmd/godoc/parser.go
@@ -18,7 +18,7 @@ import (
 )
 
 func parseFile(fset *token.FileSet, filename string, mode uint) (*ast.File, os.Error) {
-	src, err := fs.ReadFile(filename)
+	src, err := ReadFile(fs, filename)
 	if err != nil {
 		return nil, err
 	}
diff --git a/src/cmd/godoc/zip.go b/src/cmd/godoc/zip.go
index 46d7112e517..86cd79b17b1 100644
--- a/src/cmd/godoc/zip.go
+++ b/src/cmd/godoc/zip.go
@@ -22,7 +22,6 @@ import (
 	"archive/zip"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"os"
 	"path"
 	"sort"
@@ -153,14 +152,6 @@ func (fs *zipFS) ReadDir(abspath string) ([]FileInfo, os.Error) {
 	return list, nil
 }
 
-func (fs *zipFS) ReadFile(abspath string) ([]byte, os.Error) {
-	rc, err := fs.Open(abspath)
-	if err != nil {
-		return nil, err
-	}
-	return ioutil.ReadAll(rc)
-}
-
 func NewZipFS(rc *zip.ReadCloser) FileSystem {
 	list := make(zipList, len(rc.File))
 	copy(list, rc.File) // sort a copy of rc.File