diff --git a/go/gcimporter15/exportdata.go b/go/gcimporter15/exportdata.go
index 4e1d1e47..988a45b7 100644
--- a/go/gcimporter15/exportdata.go
+++ b/go/gcimporter15/exportdata.go
@@ -12,7 +12,6 @@ package gcimporter
 
 import (
 	"bufio"
-	"errors"
 	"fmt"
 	"io"
 	"strconv"
@@ -33,7 +32,7 @@ func readGopackHeader(r *bufio.Reader) (name string, size int, err error) {
 	s := strings.TrimSpace(string(hdr[16+12+6+6+8:][:10]))
 	size, err = strconv.Atoi(s)
 	if err != nil || hdr[len(hdr)-2] != '`' || hdr[len(hdr)-1] != '\n' {
-		err = errors.New("invalid archive header")
+		err = fmt.Errorf("invalid archive header")
 		return
 	}
 	name = strings.TrimSpace(string(hdr[:16]))
@@ -50,47 +49,27 @@ func FindExportData(r *bufio.Reader) (hdr string, err error) {
 	// Read first line to make sure this is an object file.
 	line, err := r.ReadSlice('\n')
 	if err != nil {
+		err = fmt.Errorf("can't find export data (%v)", err)
 		return
 	}
 
 	if string(line) == "!<arch>\n" {
 		// Archive file. Scan to __.PKGDEF.
 		var name string
-		var size int
-		if name, size, err = readGopackHeader(r); err != nil {
+		if name, _, err = readGopackHeader(r); err != nil {
 			return
 		}
 
-		// Optional leading __.GOSYMDEF or __.SYMDEF.
-		// Read and discard.
-		if name == "__.SYMDEF" || name == "__.GOSYMDEF" {
-			const block = 4096
-			tmp := make([]byte, block)
-			for size > 0 {
-				n := size
-				if n > block {
-					n = block
-				}
-				if _, err = io.ReadFull(r, tmp[:n]); err != nil {
-					return
-				}
-				size -= n
-			}
-
-			if name, _, err = readGopackHeader(r); err != nil {
-				return
-			}
-		}
-
-		// First real entry should be __.PKGDEF.
+		// First entry should be __.PKGDEF.
 		if name != "__.PKGDEF" {
-			err = errors.New("go archive is missing __.PKGDEF")
+			err = fmt.Errorf("go archive is missing __.PKGDEF")
 			return
 		}
 
 		// Read first line of __.PKGDEF data, so that line
 		// is once again the first line of the input.
 		if line, err = r.ReadSlice('\n'); err != nil {
+			err = fmt.Errorf("can't find export data (%v)", err)
 			return
 		}
 	}
@@ -98,7 +77,7 @@ func FindExportData(r *bufio.Reader) (hdr string, err error) {
 	// Now at __.PKGDEF in archive or still at beginning of file.
 	// Either way, line should begin with "go object ".
 	if !strings.HasPrefix(string(line), "go object ") {
-		err = errors.New("not a go object file")
+		err = fmt.Errorf("not a Go object file")
 		return
 	}
 
@@ -106,6 +85,7 @@ func FindExportData(r *bufio.Reader) (hdr string, err error) {
 	// Begins after first line starting with $$.
 	for line[0] != '$' {
 		if line, err = r.ReadSlice('\n'); err != nil {
+			err = fmt.Errorf("can't find export data (%v)", err)
 			return
 		}
 	}