diff --git a/packages/cache/cache.go b/packages/cache/cache.go
index 1d60812..0089179 100644
--- a/packages/cache/cache.go
+++ b/packages/cache/cache.go
@@ -16,6 +16,7 @@ package cache
 import (
 	"bytes"
 	"errors"
+	"io"
 	"os"
 	"os/exec"
 	"strconv"
@@ -84,21 +85,21 @@ func (p *Impl) Prepare(dir string, pkgPath ...string) (err error) {
 }
 
 // Find finds the cache for a pkgPath.
-func (p *Impl) Find(dir, pkgPath string) (expfile string, err error) {
+func (p *Impl) Find(dir, pkgPath string) (f io.ReadCloser, err error) {
 	val, ok := p.cache.Load(pkgPath)
-	if !ok || isDirty(pkgPath, val, p.h) {
+	if !ok || isDirty(&f, pkgPath, val, p.h) {
 		err = p.Prepare(dir, pkgPath)
-		if val, ok = p.cache.Load(pkgPath); !ok {
-			if err == nil {
-				err = os.ErrNotExist
-			}
-			return
+		if val, ok = p.cache.Load(pkgPath); ok {
+			return os.Open(val.(*pkgCache).expfile)
+		}
+		if err == nil {
+			err = os.ErrNotExist
 		}
 	}
-	return val.(*pkgCache).expfile, nil
+	return
 }
 
-func isDirty(pkgPath string, val any, h PkgHash) bool {
+func isDirty(pf *io.ReadCloser, pkgPath string, val any, h PkgHash) bool {
 	pkg := val.(*pkgCache)
 	if pkg.hash == HashInvalid || h(pkgPath, true) != pkg.hash {
 		return true
@@ -108,7 +109,9 @@ func isDirty(pkgPath string, val any, h PkgHash) bool {
 			return true
 		}
 	}
-	return false
+	f, err := os.Open(pkg.expfile)
+	*pf = f
+	return err != nil
 }
 
 type exportPkg struct {
diff --git a/packages/cache/cache_test.go b/packages/cache/cache_test.go
index 3e7c941..32a9e2b 100644
--- a/packages/cache/cache_test.go
+++ b/packages/cache/cache_test.go
@@ -109,7 +109,7 @@ func TestIsDirty(t *testing.T) {
 	c := &pkgCache{"1.a", "a", []depPkg{
 		{"b", "b"},
 	}}
-	if !isDirty("a", c, func(pkgPath string, self bool) (hash string) {
+	if !isDirty(nil, "a", c, func(pkgPath string, self bool) (hash string) {
 		if self {
 			return pkgPath
 		}
diff --git a/packages/imp.go b/packages/imp.go
index bbc5a2e..373dedd 100644
--- a/packages/imp.go
+++ b/packages/imp.go
@@ -18,6 +18,7 @@ import (
 	"errors"
 	"go/token"
 	"go/types"
+	"io"
 	"os"
 	"os/exec"
 	"sync"
@@ -30,7 +31,7 @@ import (
 
 // Cache represents a cache for the importer.
 type Cache interface {
-	Find(dir, pkgPath string) (expfile string, err error)
+	Find(dir, pkgPath string) (f io.ReadCloser, err error)
 }
 
 // Importer represents a Go package importer.
@@ -87,20 +88,15 @@ func (p *Importer) ImportFrom(pkgPath, dir string, mode types.ImportMode) (*type
 		return ret, nil
 	}
 	p.m.RUnlock()
-	expfile, err := p.findExport(dir, pkgPath)
-	if err != nil {
-		return nil, err
-	}
-	return p.loadByExport(expfile, pkgPath)
-}
-
-func (p *Importer) loadByExport(expfile string, pkgPath string) (ret *types.Package, err error) {
-	f, err := os.Open(expfile)
+	f, err := p.findExport(dir, pkgPath)
 	if err != nil {
 		return nil, err
 	}
 	defer f.Close()
+	return p.loadByExport(f, pkgPath)
+}
 
+func (p *Importer) loadByExport(f io.ReadCloser, pkgPath string) (ret *types.Package, err error) {
 	r, err := gcexportdata.NewReader(f)
 	if err == nil {
 		p.m.Lock() // use mutex because Import should be multi-thread safe
@@ -113,7 +109,7 @@ func (p *Importer) loadByExport(expfile string, pkgPath string) (ret *types.Pack
 // ----------------------------------------------------------------------------
 
 // findExport lookups export file (.a) of a package by its pkgPath.
-func (p *Importer) findExport(dir, pkgPath string) (expfile string, err error) {
+func (p *Importer) findExport(dir, pkgPath string) (f io.ReadCloser, err error) {
 	if c := p.cache; c != nil {
 		return c.Find(dir, pkgPath)
 	}
@@ -122,8 +118,8 @@ func (p *Importer) findExport(dir, pkgPath string) (expfile string, err error) {
 	if err != nil {
 		return
 	}
-	expfile = string(bytes.TrimSuffix(data, []byte{'\n'}))
-	return
+	expfile := string(bytes.TrimSuffix(data, []byte{'\n'}))
+	return os.Open(expfile)
 }
 
 func golistExport(dir, pkgPath string) (ret []byte, err error) {
diff --git a/packages/imp_test.go b/packages/imp_test.go
index 24363f4..841ef4b 100644
--- a/packages/imp_test.go
+++ b/packages/imp_test.go
@@ -14,6 +14,8 @@
 package packages
 
 import (
+	"go/types"
+	"io"
 	"os"
 	"testing"
 )
@@ -50,10 +52,20 @@ func TestImportBuiltin(t *testing.T) {
 
 func Test_loadByExport(t *testing.T) {
 	p := NewImporter(nil)
-	if _, err := p.loadByExport("/not-found", "notfound"); !os.IsNotExist(err) {
+	if _, err := loadByExport(p, "/not-found", "notfound"); !os.IsNotExist(err) {
+		t.Fatal("Test_loadByExport:", err)
+	}
+	if _, err := p.findExport(".", "C"); err == nil {
 		t.Fatal("Test_loadByExport: no error?")
 	}
-	p.findExport(".", "C")
+}
+
+func loadByExport(p *Importer, expfile, pkgPath string) (pkg *types.Package, err error) {
+	f, err := os.Open(expfile)
+	if err != nil {
+		return
+	}
+	return p.loadByExport(f, pkgPath)
 }
 
 // ----------------------------------------------------------------------------
@@ -62,11 +74,11 @@ type diskCache struct {
 	imp *Importer
 }
 
-func (p diskCache) Find(dir, pkgPath string) (expfile string, err error) {
+func (p diskCache) Find(dir, pkgPath string) (f io.ReadCloser, err error) {
 	if p.imp != nil {
 		return p.imp.findExport(dir, pkgPath)
 	}
-	return "", os.ErrNotExist
+	return nil, os.ErrNotExist
 }
 
 func TestCache(t *testing.T) {