diff --git a/components/app_update/esp_ota_ops.c b/components/app_update/esp_ota_ops.c
index 6416b5d93..74cf1a193 100644
--- a/components/app_update/esp_ota_ops.c
+++ b/components/app_update/esp_ota_ops.c
@@ -145,8 +145,7 @@ esp_err_t esp_ota_write(esp_ota_handle_t handle, const void *data, size_t size)
         if (it->handle == handle) {
             // must erase the partition before writing to it
             assert(it->erased_size > 0 && "must erase the partition before writing to it");
-
-            if(it->wrote_size == 0 && size > 0 && data_bytes[0] != 0xE9) {
+            if(it->wrote_size == 0 && it->partial_bytes == 0 && size > 0 && data_bytes[0] != 0xE9) {
                 ESP_LOGE(TAG, "OTA image has invalid magic byte (expected 0xE9, saw 0x%02x", data_bytes[0]);
                 return ESP_ERR_OTA_VALIDATE_FAILED;
             }