diff --git a/gopls/internal/hooks/gen-licenses.sh b/gopls/internal/hooks/gen-licenses.sh
index f0756ff..7d6bab7 100755
--- a/gopls/internal/hooks/gen-licenses.sh
+++ b/gopls/internal/hooks/gen-licenses.sh
@@ -6,13 +6,10 @@
 
 set -o pipefail
 
+output=$1
 tempfile=$(mktemp)
 cd $(dirname $0)
 
-modhash=$(sha256sum ../../go.sum | awk '{print $1}')
-# Make sure we have the code for all the modules we depend on.
-go mod download
-
 cat > $tempfile <<END
 // Copyright 2020 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
@@ -37,9 +34,5 @@
   echo >> $tempfile
 done
 
-cat >> $tempfile << END
-\`
-
-const licensesGeneratedFrom = "$modhash"
-END
-mv $tempfile licenses.go
\ No newline at end of file
+echo "\`" >> $tempfile
+mv $tempfile $output
\ No newline at end of file
diff --git a/gopls/internal/hooks/licenses.go b/gopls/internal/hooks/licenses.go
index 028c90e..a159465 100644
--- a/gopls/internal/hooks/licenses.go
+++ b/gopls/internal/hooks/licenses.go
@@ -167,5 +167,3 @@
 OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 `
-
-const licensesGeneratedFrom = "029a0f934a7bad22a7d47185055bc554b1ea23ce427351caa87d9a088fcfba4e"
diff --git a/gopls/internal/hooks/licenses_test.go b/gopls/internal/hooks/licenses_test.go
index 28b1149..d2c4e34 100644
--- a/gopls/internal/hooks/licenses_test.go
+++ b/gopls/internal/hooks/licenses_test.go
@@ -5,19 +5,36 @@
 package hooks
 
 import (
-	"crypto/sha256"
-	"encoding/hex"
+	"bytes"
 	"io/ioutil"
+	"os/exec"
+	"runtime"
 	"testing"
 )
 
 func TestLicenses(t *testing.T) {
-	sumBytes, err := ioutil.ReadFile("../../go.sum")
+	if runtime.GOOS != "linux" && runtime.GOOS != "darwin" {
+		t.Skip("generating licenses only works on Unixes")
+	}
+	tmp, err := ioutil.TempFile("", "")
 	if err != nil {
 		t.Fatal(err)
 	}
-	sumSum := sha256.Sum256(sumBytes)
-	if licensesGeneratedFrom != hex.EncodeToString(sumSum[:]) {
+	tmp.Close()
+
+	if out, err := exec.Command("./gen-licenses.sh", tmp.Name()).CombinedOutput(); err != nil {
+		t.Fatalf("generating licenses failed: %q, %v", out, err)
+	}
+
+	got, err := ioutil.ReadFile(tmp.Name())
+	if err != nil {
+		t.Fatal(err)
+	}
+	want, err := ioutil.ReadFile("licenses.go")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(got, want) {
 		t.Error("combined license text needs updating. Run: `go generate ./internal/hooks` from the gopls module.")
 	}
 }