diff --git a/src/cmd/go/internal/modfetch/fetch.go b/src/cmd/go/internal/modfetch/fetch.go
index 51a56028c4..2eead5f746 100644
--- a/src/cmd/go/internal/modfetch/fetch.go
+++ b/src/cmd/go/internal/modfetch/fetch.go
@@ -7,6 +7,7 @@ package modfetch
 import (
 	"archive/zip"
 	"bytes"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -361,19 +362,19 @@ func checkMod(mod module.Version) {
 	// Do the file I/O before acquiring the go.sum lock.
 	ziphash, err := CachePath(mod, "ziphash")
 	if err != nil {
-		base.Fatalf("verifying %s@%s: %v", mod.Path, mod.Version, err)
+		base.Fatalf("verifying %v", module.VersionError(mod, err))
 	}
 	data, err := renameio.ReadFile(ziphash)
 	if err != nil {
-		if os.IsNotExist(err) {
+		if errors.Is(err, os.ErrNotExist) {
 			// This can happen if someone does rm -rf GOPATH/src/cache/download. So it goes.
 			return
 		}
-		base.Fatalf("verifying %s@%s: %v", mod.Path, mod.Version, err)
+		base.Fatalf("verifying %v", module.VersionError(mod, err))
 	}
 	h := strings.TrimSpace(string(data))
 	if !strings.HasPrefix(h, "h1:") {
-		base.Fatalf("verifying %s@%s: unexpected ziphash: %q", mod.Path, mod.Version, h)
+		base.Fatalf("verifying %v", module.VersionError(mod, fmt.Errorf("unexpected ziphash: %q", h)))
 	}
 
 	checkModSum(mod, h)