diff --git a/pio-tools/post_esp32.py b/pio-tools/post_esp32.py
index eb1da1285..ab3440ea7 100644
--- a/pio-tools/post_esp32.py
+++ b/pio-tools/post_esp32.py
@@ -135,7 +135,7 @@ def esp32_create_combined_bin(source, target, env):
     flash_freq = env.BoardConfig().get("build.f_flash", "40000000L")
     flash_freq = str(flash_freq).replace("L", "")
     flash_freq = str(int(int(flash_freq) / 1000000)) + "m"
-    flash_mode = env.BoardConfig().get("build.flash_mode", "dout")
+    flash_mode = env.BoardConfig().get("build.flash_mode", "dio")
     if flash_mode == "qio":
         flash_mode = "dio"
     elif flash_mode == "qout":