diff --git a/builder/main.py b/builder/main.py
index 3c4eefb..fe1246d 100644
--- a/builder/main.py
+++ b/builder/main.py
@@ -368,7 +368,7 @@ elif upload_protocol == "esptool":
             "write_flash", "-z",
             "--flash_mode", "${__get_board_flash_mode(__env__)}",
             "--flash_freq", "${__get_board_f_flash(__env__)}",
-            "--flash_size", "detect",
+            "--flash_size", board.get("upload.flash_size", "detect"),
             board.get("upload.offset_address", "$ESP32_APP_OFFSET"),
             "$SOURCE"
         ],