diff --git a/client_examples_test.go b/client_examples_test.go
index 57a8d9f..e3c0f09 100644
--- a/client_examples_test.go
+++ b/client_examples_test.go
@@ -77,7 +77,7 @@ func ExampleClient_BuildBaseURL() {
 // Retrieve the content of a m.room.name state event.
 func ExampleClient_StateEvent() {
 	content := struct {
-		name string `json:"name"`
+		Name string `json:"name"`
 	}{}
 	cli, _ := NewClient("https://matrix.org", "@example:matrix.org", "abcdef123456")
 	if err := cli.StateEvent("!foo:bar", "m.room.name", "", &content); err != nil {
diff --git a/hooks/pre-commit b/hooks/pre-commit
index 6a14ccf..41df674 100755
--- a/hooks/pre-commit
+++ b/hooks/pre-commit
@@ -4,6 +4,6 @@ set -eu
 
 golint
 go fmt
-go tool vet --shadow .
+go tool vet --all --shadow .
 gocyclo -over 12 .
 go test -timeout 5s -test.v
diff --git a/userids.go b/userids.go
index 817a006..23e7807 100644
--- a/userids.go
+++ b/userids.go
@@ -121,7 +121,7 @@ func DecodeUserLocalpart(str string) (string, error) {
 // See http://matrix.org/docs/spec/intro.html#user-identifiers
 func ExtractUserLocalpart(userID string) (string, error) {
 	if len(userID) == 0 || userID[0] != '@' {
-		return "", fmt.Errorf("%s is not a valid user id")
+		return "", fmt.Errorf("%s is not a valid user id", userID)
 	}
 	return strings.TrimPrefix(
 		strings.SplitN(userID, ":", 2)[0], // @foo:bar:8448 => [ "@foo", "bar:8448" ]