diff --git a/cmd/apidiff/main.go b/cmd/apidiff/main.go
index d29c90f..a5446b7 100644
--- a/cmd/apidiff/main.go
+++ b/cmd/apidiff/main.go
@@ -2,6 +2,7 @@
 package main
 
 import (
+	"bufio"
 	"flag"
 	"fmt"
 	"go/token"
@@ -109,7 +110,14 @@
 		return nil, err
 	}
 	defer f.Close()
-	return gcexportdata.Read(f, token.NewFileSet(), map[string]*types.Package{}, filename)
+	r := bufio.NewReader(f)
+	m := map[string]*types.Package{}
+	pkgPath, err := r.ReadString('\n')
+	if err != nil {
+		return nil, err
+	}
+	pkgPath = pkgPath[:len(pkgPath)-1] // remove delimiter
+	return gcexportdata.Read(r, token.NewFileSet(), m, pkgPath)
 }
 
 func writeExportData(pkg *packages.Package, filename string) error {
@@ -117,6 +125,9 @@
 	if err != nil {
 		return err
 	}
+	// Include the package path in the file. The exportdata format does
+	// not record the path of the package being written.
+	fmt.Fprintln(f, pkg.PkgPath)
 	err1 := gcexportdata.Write(f, pkg.Fset, pkg.Types)
 	err2 := f.Close()
 	if err1 != nil {
diff --git a/go.mod b/go.mod
index 7df64e7..796d190 100644
--- a/go.mod
+++ b/go.mod
@@ -10,5 +10,5 @@
 	golang.org/x/mobile v0.0.0-20190719004257-d2bd2a29d028
 	golang.org/x/mod v0.1.0
 	golang.org/x/sys v0.0.0-20190412213103-97732733099d
-	golang.org/x/tools v0.0.0-20190927191325-030b2cf1153e
+	golang.org/x/tools v0.0.0-20191012152004-8de300cfc20a
 )
diff --git a/go.sum b/go.sum
index 9edbeec..f4283c5 100644
--- a/go.sum
+++ b/go.sum
@@ -25,4 +25,6 @@
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/tools v0.0.0-20190927191325-030b2cf1153e h1:1xWUkZQQ9Z9UuZgNaIR6OQOE7rUFglXUUBZlO+dGg6I=
 golang.org/x/tools v0.0.0-20190927191325-030b2cf1153e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.0.0-20191012152004-8de300cfc20a h1:TwMENskLwU2NnWBzrJGEWHqSiGUkO/B4rfyhwqDxDYQ=
+golang.org/x/tools v0.0.0-20191012152004-8de300cfc20a/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=