diff --git a/internal/build/build.go b/internal/build/build.go
index d2a77cbb..f283130a 100644
--- a/internal/build/build.go
+++ b/internal/build/build.go
@@ -106,8 +106,7 @@ func Do(args []string, conf *Config) {
 
 	prog := llssa.NewProgram(nil)
 	sizes := prog.TypeSizes
-	// dedup := packages.NewDeduper()
-	dedup := (*packages.Deduper)(nil)
+	dedup := packages.NewDeduper()
 
 	if patterns == nil {
 		patterns = []string{"."}
diff --git a/internal/packages/load.go b/internal/packages/load.go
index 22e4fbb6..49b81d8f 100644
--- a/internal/packages/load.go
+++ b/internal/packages/load.go
@@ -17,14 +17,12 @@
 package packages
 
 import (
-	"errors"
 	"fmt"
 	"go/types"
 	"runtime"
 	"sync"
 	"unsafe"
 
-	"golang.org/x/sync/errgroup"
 	"golang.org/x/tools/go/packages"
 )
 
@@ -59,12 +57,6 @@ const (
 // Calls to Load do not modify this struct.
 type Config = packages.Config
 
-func setGoListOverlayFile(cfg *Config, val string) {
-	// TODO(xsw): suppose that the field is at the end of the struct
-	ptr := uintptr(unsafe.Pointer(cfg)) + (unsafe.Sizeof(*cfg) - unsafe.Sizeof(val))
-	*(*string)(unsafe.Pointer(ptr)) = val
-}
-
 // A Package describes a loaded Go package.
 type Package = packages.Package
 
@@ -86,127 +78,15 @@ type loader struct {
 	requestedMode LoadMode
 }
 
-// Deduper wraps a DriverResponse, deduplicating its contents.
 type Deduper struct {
-	seenRoots    map[string]bool
-	seenPackages map[string]*Package
-	dr           *packages.DriverResponse // TODO(xsw): ensure offset of dr
 }
 
-//go:linkname NewDeduper golang.org/x/tools/go/packages.newDeduper
-func NewDeduper() *Deduper
-
-//go:linkname addAll golang.org/x/tools/go/packages.(*responseDeduper).addAll
-func addAll(r *Deduper, dr *packages.DriverResponse)
-
-func mergeResponsesEx(dedup *Deduper, responses ...*packages.DriverResponse) *packages.DriverResponse {
-	if len(responses) == 0 {
-		return nil
-	}
-	if dedup == nil {
-		dedup = NewDeduper()
-	}
-	response := dedup
-	response.dr.NotHandled = false
-	response.dr.Compiler = responses[0].Compiler
-	response.dr.Arch = responses[0].Arch
-	response.dr.GoVersion = responses[0].GoVersion
-	for _, v := range responses {
-		addAll(response, v)
-	}
-	return response.dr
+func NewDeduper() *Deduper {
+	return nil
 }
 
-// driver is the type for functions that query the build system for the
-// packages named by the patterns.
-type driver func(cfg *Config, patterns ...string) (*packages.DriverResponse, error)
-
-func callDriverOnChunksEx(dedup *Deduper, driver driver, cfg *Config, chunks [][]string) (*packages.DriverResponse, error) {
-	if len(chunks) == 0 {
-		return driver(cfg)
-	}
-	responses := make([]*packages.DriverResponse, len(chunks))
-	errNotHandled := errors.New("driver returned NotHandled")
-	var g errgroup.Group
-	for i, chunk := range chunks {
-		i := i
-		chunk := chunk
-		g.Go(func() (err error) {
-			responses[i], err = driver(cfg, chunk...)
-			if responses[i] != nil && responses[i].NotHandled {
-				err = errNotHandled
-			}
-			return err
-		})
-	}
-	if err := g.Wait(); err != nil {
-		if errors.Is(err, errNotHandled) {
-			return &packages.DriverResponse{NotHandled: true}, nil
-		}
-		return nil, err
-	}
-	return mergeResponsesEx(dedup, responses...), nil
-}
-
-//go:linkname splitIntoChunks golang.org/x/tools/go/packages.splitIntoChunks
-func splitIntoChunks(patterns []string, argMax int) ([][]string, error)
-
-//go:linkname findExternalDriver golang.org/x/tools/go/packages.findExternalDriver
-func findExternalDriver(cfg *Config) driver
-
-//go:linkname goListDriver golang.org/x/tools/go/packages.goListDriver
-func goListDriver(cfg *Config, patterns ...string) (_ *packages.DriverResponse, err error)
-
-//go:linkname writeOverlays golang.org/x/tools/internal/gocommand.WriteOverlays
-func writeOverlays(overlay map[string][]byte) (filename string, cleanup func(), err error)
-
-func defaultDriverEx(dedup *Deduper, cfg *Config, patterns ...string) (*packages.DriverResponse, bool, error) {
-	const (
-		// windowsArgMax specifies the maximum command line length for
-		// the Windows' CreateProcess function.
-		windowsArgMax = 32767
-		// maxEnvSize is a very rough estimation of the maximum environment
-		// size of a user.
-		maxEnvSize = 16384
-		// safeArgMax specifies the maximum safe command line length to use
-		// by the underlying driver excl. the environment. We choose the Windows'
-		// ARG_MAX as the starting point because it's one of the lowest ARG_MAX
-		// constants out of the different supported platforms,
-		// e.g., https://www.in-ulm.de/~mascheck/various/argmax/#results.
-		safeArgMax = windowsArgMax - maxEnvSize
-	)
-	chunks, err := splitIntoChunks(patterns, safeArgMax)
-	if err != nil {
-		return nil, false, err
-	}
-
-	if driver := findExternalDriver(cfg); driver != nil {
-		response, err := callDriverOnChunksEx(dedup, driver, cfg, chunks)
-		if err != nil {
-			return nil, false, err
-		} else if !response.NotHandled {
-			return response, true, nil
-		}
-		// (fall through)
-	}
-
-	// go list fallback
-	//
-	// Write overlays once, as there are many calls
-	// to 'go list' (one per chunk plus others too).
-	overlay, cleanupOverlay, err := writeOverlays(cfg.Overlay)
-	if err != nil {
-		return nil, false, err
-	}
-	defer cleanupOverlay()
-	setGoListOverlayFile(cfg, overlay)
-
-	response, err := callDriverOnChunksEx(dedup, goListDriver, cfg, chunks)
-	if err != nil {
-		return nil, false, err
-	}
-	return response, false, err
-}
+//go:linkname defaultDriver golang.org/x/tools/go/packages.defaultDriver
+func defaultDriver(cfg *Config, patterns ...string) (*packages.DriverResponse, bool, error)
 
 //go:linkname newLoader golang.org/x/tools/go/packages.newLoader
 func newLoader(cfg *Config) *loader
@@ -230,7 +110,7 @@ func refine(ld *loader, response *packages.DriverResponse) ([]*Package, error)
 // provided for convenient display of all errors.
 func LoadEx(dedup *Deduper, sizes func(types.Sizes) types.Sizes, cfg *Config, patterns ...string) ([]*Package, error) {
 	ld := newLoader(cfg)
-	response, external, err := defaultDriverEx(dedup, &ld.Config, patterns...)
+	response, external, err := defaultDriver(&ld.Config, patterns...)
 	if err != nil {
 		return nil, err
 	}