diff --git a/components/esp32/system_api.c b/components/esp32/system_api.c
index 93763e523..7edb8a699 100644
--- a/components/esp32/system_api.c
+++ b/components/esp32/system_api.c
@@ -211,14 +211,15 @@ esp_err_t esp_read_mac(uint8_t* mac, esp_mac_type_t type)
 
 esp_err_t esp_register_shutdown_handler(shutdown_handler_t handler)
 {
-     int i;
-     for (i = 0; i < SHUTDOWN_HANDLERS_NO; i++) {
-	  if (shutdown_handlers[i] == NULL) {
-	       shutdown_handlers[i] = handler;
-	       return ESP_OK;
-	  }
-     }
-     return ESP_FAIL;
+    for (int i = 0; i < SHUTDOWN_HANDLERS_NO; i++) {
+        if (shutdown_handlers[i] == handler) {
+            return ESP_ERR_INVALID_STATE;
+        } else if (shutdown_handlers[i] == NULL) {
+            shutdown_handlers[i] = handler;
+            return ESP_OK;
+        }
+    }
+    return ESP_ERR_NO_MEM;
 }
 
 esp_err_t esp_unregister_shutdown_handler(shutdown_handler_t handler)
diff --git a/components/esp_common/include/esp_system.h b/components/esp_common/include/esp_system.h
index 5de5e5a9a..f73165a1e 100644
--- a/components/esp_common/include/esp_system.h
+++ b/components/esp_common/include/esp_system.h
@@ -80,6 +80,11 @@ typedef void (*shutdown_handler_t)(void);
   *
   * This function allows you to register a handler that gets invoked before
   * the application is restarted using esp_restart function.
+  * @param handle function to execute on restart
+  * @return
+  *   - ESP_OK on success
+  *   - ESP_ERR_INVALID_STATE if the handler has already been registered
+  *   - ESP_ERR_NO_MEM if no more shutdown handler slots are available
   */
 esp_err_t esp_register_shutdown_handler(shutdown_handler_t handle);