diff --git a/config/config.go b/config/config.go
index 8cdb11d..e508714 100644
--- a/config/config.go
+++ b/config/config.go
@@ -277,10 +277,17 @@ type SectionGRPC struct {
 	Port    string `yaml:"port"`
 }
 
+func setDefault() {
+	viper.SetDefault("ios.max_concurrent_pushes", uint(100))
+}
+
 // LoadConf load config from file and read in environment variables that match
 func LoadConf(confPath ...string) (*ConfYaml, error) {
 	conf := &ConfYaml{}
 
+	// load default values
+	setDefault()
+
 	viper.SetConfigType("yaml")
 	viper.AutomaticEnv()         // read in environment variables that match
 	viper.SetEnvPrefix("gorush") // will be uppercased automatically
diff --git a/config/config_test.go b/config/config_test.go
index ec3df03..9b957c5 100644
--- a/config/config_test.go
+++ b/config/config_test.go
@@ -17,6 +17,15 @@ func TestMissingFile(t *testing.T) {
 	assert.NotNil(t, err)
 }
 
+func TestEmptyConfig(t *testing.T) {
+	conf, err := LoadConf("testdata/empty.yml")
+	if err != nil {
+		panic("failed to load config.yml from file")
+	}
+
+	assert.Equal(t, uint(100), conf.Ios.MaxConcurrentPushes)
+}
+
 type ConfigTestSuite struct {
 	suite.Suite
 	ConfGorushDefault *ConfYaml
diff --git a/config/testdata/empty.yml b/config/testdata/empty.yml
new file mode 100644
index 0000000..e69de29