diff --git a/go/internal/gcimporter/bexport_test.go b/go/internal/gcimporter/bexport_test.go
index de7b921af0..73585a68ee 100644
--- a/go/internal/gcimporter/bexport_test.go
+++ b/go/internal/gcimporter/bexport_test.go
@@ -12,6 +12,7 @@ import (
 	"go/parser"
 	"go/token"
 	"go/types"
+	"path/filepath"
 	"reflect"
 	"runtime"
 	"strings"
@@ -117,7 +118,8 @@ type UnknownType undefined
 
 func fileLine(fset *token.FileSet, obj types.Object) string {
 	posn := fset.Position(obj.Pos())
-	return fmt.Sprintf("%s:%d", posn.Filename, posn.Line)
+	filename := filepath.Clean(strings.ReplaceAll(posn.Filename, "$GOROOT", build.Default.GOROOT))
+	return fmt.Sprintf("%s:%d", filename, posn.Line)
 }
 
 // equalObj reports how x and y differ.  They are assumed to belong to
diff --git a/go/internal/gcimporter/iexport.go b/go/internal/gcimporter/iexport.go
index 144948c822..c4fae426de 100644
--- a/go/internal/gcimporter/iexport.go
+++ b/go/internal/gcimporter/iexport.go
@@ -472,10 +472,10 @@ func (w *exportWriter) param(obj types.Object) {
 func (w *exportWriter) value(typ types.Type, v constant.Value) {
 	w.typ(typ, nil)
 
-	switch v.Kind() {
-	case constant.Bool:
+	switch b := typ.Underlying().(*types.Basic); b.Info() & types.IsConstType {
+	case types.IsBoolean:
 		w.bool(constant.BoolVal(v))
-	case constant.Int:
+	case types.IsInteger:
 		var i big.Int
 		if i64, exact := constant.Int64Val(v); exact {
 			i.SetInt64(i64)
@@ -485,25 +485,27 @@ func (w *exportWriter) value(typ types.Type, v constant.Value) {
 			i.SetString(v.ExactString(), 10)
 		}
 		w.mpint(&i, typ)
-	case constant.Float:
+	case types.IsFloat:
 		f := constantToFloat(v)
 		w.mpfloat(f, typ)
-	case constant.Complex:
+	case types.IsComplex:
 		w.mpfloat(constantToFloat(constant.Real(v)), typ)
 		w.mpfloat(constantToFloat(constant.Imag(v)), typ)
-	case constant.String:
+	case types.IsString:
 		w.string(constant.StringVal(v))
-	case constant.Unknown:
-		// package contains type errors
 	default:
-		panic(internalErrorf("unexpected value %v (%T)", v, v))
+		if b.Kind() == types.Invalid {
+			// package contains type errors
+			break
+		}
+		panic(internalErrorf("unexpected type %v (%v)", typ, typ.Underlying()))
 	}
 }
 
 // constantToFloat converts a constant.Value with kind constant.Float to a
 // big.Float.
 func constantToFloat(x constant.Value) *big.Float {
-	assert(x.Kind() == constant.Float)
+	x = constant.ToFloat(x)
 	// Use the same floating-point precision (512) as cmd/compile
 	// (see Mpprec in cmd/compile/internal/gc/mpfloat.go).
 	const mpprec = 512
diff --git a/go/internal/gcimporter/iexport_test.go b/go/internal/gcimporter/iexport_test.go
index 6839844082..8284edeac7 100644
--- a/go/internal/gcimporter/iexport_test.go
+++ b/go/internal/gcimporter/iexport_test.go
@@ -9,6 +9,7 @@
 package gcimporter_test
 
 import (
+	"bufio"
 	"bytes"
 	"fmt"
 	"go/ast"
@@ -17,7 +18,9 @@ import (
 	"go/parser"
 	"go/token"
 	"go/types"
+	"io/ioutil"
 	"math/big"
+	"os"
 	"reflect"
 	"runtime"
 	"sort"
@@ -29,6 +32,27 @@ import (
 	"golang.org/x/tools/go/loader"
 )
 
+func readExportFile(filename string) ([]byte, error) {
+	f, err := os.Open(filename)
+	if err != nil {
+		return nil, err
+	}
+	defer f.Close()
+
+	buf := bufio.NewReader(f)
+	if _, err := gcimporter.FindExportData(buf); err != nil {
+		return nil, err
+	}
+
+	if ch, err := buf.ReadByte(); err != nil {
+		return nil, err
+	} else if ch != 'i' {
+		return nil, fmt.Errorf("unexpected byte: %v", ch)
+	}
+
+	return ioutil.ReadAll(buf)
+}
+
 func iexport(fset *token.FileSet, pkg *types.Package) ([]byte, error) {
 	var buf bytes.Buffer
 	if err := gcimporter.IExportData(&buf, fset, pkg); err != nil {
@@ -54,6 +78,9 @@ func TestIExportData_stdlib(t *testing.T) {
 	conf := loader.Config{
 		Build:       &ctxt,
 		AllowErrors: true,
+		TypeChecker: types.Config{
+			Sizes: types.SizesFor(ctxt.Compiler, ctxt.GOARCH),
+		},
 	}
 	for _, path := range buildutil.AllPackages(conf.Build) {
 		conf.Import(path)
@@ -96,6 +123,16 @@ type UnknownType undefined
 		} else {
 			testPkgData(t, conf.Fset, pkg, exportdata)
 		}
+
+		if pkg.Name() == "main" || pkg.Name() == "haserrors" {
+			// skip; no export data
+		} else if bp, err := ctxt.Import(pkg.Path(), "", build.FindOnly); err != nil {
+			t.Log("warning:", err)
+		} else if exportdata, err := readExportFile(bp.PkgObj); err != nil {
+			t.Log("warning:", err)
+		} else {
+			testPkgData(t, conf.Fset, pkg, exportdata)
+		}
 	}
 }
 
@@ -111,6 +148,10 @@ func testPkgData(t *testing.T, fset *token.FileSet, pkg *types.Package, exportda
 }
 
 func testPkg(t *testing.T, fset *token.FileSet, pkg *types.Package, fset2 *token.FileSet, pkg2 *types.Package) {
+	if _, err := iexport(fset2, pkg2); err != nil {
+		t.Errorf("reexport %q: %v", pkg.Path(), err)
+	}
+
 	// Compare the packages' corresponding members.
 	for _, name := range pkg.Scope().Names() {
 		if !ast.IsExported(name) {