diff --git a/main/include/nconfig.h b/main/include/nconfig.h
index d479596..63a2d87 100644
--- a/main/include/nconfig.h
+++ b/main/include/nconfig.h
@@ -31,6 +31,8 @@ enum nconfig_type
     NCONFIG_TYPE_MAX,
 };
 
+bool nconfig_value_is_not_set(enum nconfig_type type);
+
 // Write config
 esp_err_t nconfig_write(enum nconfig_type type, const char* data);
 
diff --git a/main/nconfig/nconfig.c b/main/nconfig/nconfig.c
index 0ed4911..6f80c85 100644
--- a/main/nconfig/nconfig.c
+++ b/main/nconfig/nconfig.c
@@ -52,9 +52,7 @@ esp_err_t init_nconfig()
     for (int i = 0; i < sizeof(default_values) / sizeof(default_values[0]); ++i)
     {
         // check key is not exist or value is null
-        size_t len = 0;
-        nconfig_get_str_len(default_values[i].type, &len);
-        if (len <= 1) // nconfig_get_str_len return err or value is '\0'
+        if (nconfig_value_is_not_set(default_values[i].type))
         {
             if (nconfig_write(default_values[i].type, default_values[i].value) != ESP_OK)
                 // if nconfig write fail, system panic
@@ -65,6 +63,13 @@ esp_err_t init_nconfig()
     return ESP_OK;
 }
 
+bool nconfig_value_is_not_set(enum nconfig_type type)
+{
+    size_t len = 0;
+    esp_err_t err = nconfig_get_str_len(type, &len);
+    return (err != ESP_OK || len <= 1);
+}
+
 esp_err_t nconfig_write(enum nconfig_type type, const char* data)
 {
     return nvs_set_str(handle, keys[type], data);