diff --git a/config/config.go b/config/config.go
index 5c9bcf9..4c67eac 100644
--- a/config/config.go
+++ b/config/config.go
@@ -227,7 +227,9 @@ func LoadConf(confPath string) (ConfYaml, error) {
 			return conf, err
 		}
 
-		viper.ReadConfig(bytes.NewBuffer(content))
+		if err := viper.ReadConfig(bytes.NewBuffer(content)); err != nil {
+			return conf, err
+		}
 	} else {
 		// Search config in home directory with name ".gorush" (without extension).
 		viper.AddConfigPath("/etc/gorush/")
@@ -240,7 +242,9 @@ func LoadConf(confPath string) (ConfYaml, error) {
 			fmt.Println("Using config file:", viper.ConfigFileUsed())
 		} else {
 			// load default config
-			viper.ReadConfig(bytes.NewBuffer(defaultConf))
+			if err := viper.ReadConfig(bytes.NewBuffer(defaultConf)); err != nil {
+				return conf, err
+			}
 		}
 	}
 
diff --git a/config/config_test.go b/config/config_test.go
index b8a84bf..cd019b6 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -29,7 +29,7 @@ func (suite *ConfigTestSuite) SetupTest() {
 	if err != nil {
 		panic("failed to load default config.yml")
 	}
-	suite.ConfGorush, err = LoadConf("config.yml")
+	suite.ConfGorush, err = LoadConf("testdata/config.yml")
 	if err != nil {
 		panic("failed to load config.yml from file")
 	}
@@ -75,7 +75,7 @@ func (suite *ConfigTestSuite) TestValidateConfDefault() {
 
 	// iOS
 	assert.Equal(suite.T(), false, suite.ConfGorushDefault.Ios.Enabled)
-	assert.Equal(suite.T(), "key.pem", suite.ConfGorushDefault.Ios.KeyPath)
+	assert.Equal(suite.T(), "", suite.ConfGorushDefault.Ios.KeyPath)
 	assert.Equal(suite.T(), "", suite.ConfGorushDefault.Ios.KeyBase64)
 	assert.Equal(suite.T(), "pem", suite.ConfGorushDefault.Ios.KeyType)
 	assert.Equal(suite.T(), "", suite.ConfGorushDefault.Ios.Password)
@@ -191,7 +191,7 @@ func TestLoadConfigFromEnv(t *testing.T) {
 	os.Setenv("GORUSH_IOS_KEY_ID", "ABC123DEFG")
 	os.Setenv("GORUSH_IOS_TEAM_ID", "DEF123GHIJ")
 	os.Setenv("GORUSH_API_HEALTH_URI", "/healthz")
-	ConfGorush, err := LoadConf("config.yml")
+	ConfGorush, err := LoadConf("testdata/config.yml")
 	if err != nil {
 		panic("failed to load config.yml from file")
 	}
@@ -202,3 +202,14 @@ func TestLoadConfigFromEnv(t *testing.T) {
 	assert.Equal(t, "DEF123GHIJ", ConfGorush.Ios.TeamID)
 	assert.Equal(t, "/healthz", ConfGorush.API.HealthURI)
 }
+
+func TestLoadWrongYAMLConfig(t *testing.T) {
+	_, err := LoadConf("testdata/wrong.yml")
+	assert.Error(t, err)
+}
+
+func TestLoadWrongDefaultYAMLConfig(t *testing.T) {
+	defaultConf = []byte(`a`)
+	_, err := LoadConf("")
+	assert.Error(t, err)
+}
diff --git a/config/config.yml b/config/testdata/config.yml
similarity index 100%
rename from config/config.yml
rename to config/testdata/config.yml
diff --git a/config/testdata/wrong.yml b/config/testdata/wrong.yml
new file mode 100644
index 0000000..32e57a2
--- /dev/null
+++ b/config/testdata/wrong.yml
@@ -0,0 +1,76 @@
+# wrong format
+#core:
+  core:
+  enabled: true # enabale httpd server
+  address: "" # ip address to bind (default: any)
+  port: "8088" # ignore this port number if auto_tls is enabled (listen 443).
+  worker_num: 0 # default worker number is runtime.NumCPU()
+  queue_num: 0 # default queue number is 8192
+  max_notification: 100
+  sync: false # set true if you need get error message from fail push notification in API response.
+  mode: "release"
+  ssl: false
+  cert_path: "cert.pem"
+  key_path: "key.pem"
+  cert_base64: ""
+  key_base64: ""
+  http_proxy: "" # only working for FCM server
+  pid:
+    enabled: false
+    path: "gorush.pid"
+    override: true
+  auto_tls:
+    enabled: false # Automatically install TLS certificates from Let's Encrypt.
+    folder: ".cache" # folder for storing TLS certificates
+    host: "" # which domains the Let's Encrypt will attempt
+
+grpc:
+  enabled: false # enabale gRPC server
+  port: 9000
+
+api:
+  push_uri: "/api/push"
+  stat_go_uri: "/api/stat/go"
+  stat_app_uri: "/api/stat/app"
+  config_uri: "/api/config"
+  sys_stat_uri: "/sys/stats"
+  metric_uri: "/metrics"
+  health_uri: "/healthz"
+
+android:
+  enabled: true
+  apikey: "YOUR_API_KEY"
+  max_retry: 0 # resend fail notification, default value zero is disabled
+
+ios:
+  enabled: false
+  key_path: "key.pem"
+  key_base64: "" # load iOS key from base64 input
+  key_type: "pem" # could be pem, p12 or p8 type
+  password: "" # certificate password, default as empty string.
+  production: false
+  max_retry: 0 # resend fail notification, default value zero is disabled
+  key_id: "" # KeyID from developer account (Certificates, Identifiers & Profiles -> Keys)
+  team_id: "" # TeamID from developer account (View Account -> Membership)
+
+log:
+  format: "string" # string or json
+  access_log: "stdout" # stdout: output to console, or define log path like "log/access_log"
+  access_level: "debug"
+  error_log: "stderr" # stderr: output to console, or define log path like "log/error_log"
+  error_level: "error"
+  hide_token: true
+
+stat:
+  engine: "memory" # support memory, redis, boltdb, buntdb or leveldb
+  redis:
+    addr: "localhost:6379"
+    password: ""
+    db: 0
+  boltdb:
+    path: "bolt.db"
+    bucket: "gorush"
+  buntdb:
+    path: "bunt.db"
+  leveldb:
+    path: "level.db"