diff --git a/boards/esp32-devkitlipo.json b/boards/esp32-devkitlipo.json
index 78fb525..db173b2 100644
--- a/boards/esp32-devkitlipo.json
+++ b/boards/esp32-devkitlipo.json
@@ -28,7 +28,7 @@
     "maximum_ram_size": 327680,
     "maximum_size": 4194304,
     "require_upload_port": true,
-    "speed": 921600
+    "speed": 460800
   },
   "url": "https://www.olimex.com/Products/IoT/ESP32/ESP32-DevKit-LiPo/open-source-hardware",
   "vendor": "OLIMEX"
diff --git a/boards/esp32-poe-iso.json b/boards/esp32-poe-iso.json
index 402e0c2..8fb1268 100644
--- a/boards/esp32-poe-iso.json
+++ b/boards/esp32-poe-iso.json
@@ -25,7 +25,7 @@
     "maximum_ram_size": 327680,
     "maximum_size": 4194304,
     "require_upload_port": true,
-    "speed": 921600
+    "speed": 460800
   },
   "url": "https://www.olimex.com/Products/IoT/ESP32/ESP32-POE-ISO/open-source-hardware",
   "vendor": "OLIMEX"
diff --git a/boards/magicbit.json b/boards/magicbit.json
index 7a59fac..5afeac8 100644
--- a/boards/magicbit.json
+++ b/boards/magicbit.json
@@ -25,7 +25,7 @@
     "maximum_ram_size": 327680,
     "maximum_size": 4194304,
     "require_upload_port": true,
-    "speed": 921600
+    "speed": 460800
   },
   "url": "http://magicblocks.io/",
   "vendor": "Magicblocks.io"
diff --git a/boards/pycom_gpy.json b/boards/pycom_gpy.json
index f922203..445447e 100644
--- a/boards/pycom_gpy.json
+++ b/boards/pycom_gpy.json
@@ -25,7 +25,7 @@
     "maximum_ram_size": 327680,
     "maximum_size": 4194304,
     "require_upload_port": true,
-    "speed": 921600
+    "speed": 460800
   },
   "url": "https://pycom.io/product/gpy/",
   "vendor": "Pycom Ltd."
diff --git a/boards/tinypico.json b/boards/tinypico.json
index 136f552..395f529 100644
--- a/boards/tinypico.json
+++ b/boards/tinypico.json
@@ -25,7 +25,7 @@
     "maximum_ram_size": 327680,
     "maximum_size": 4194304,
     "require_upload_port": true,
-    "speed": 921600
+    "speed": 460800
   },
   "url": "https://www.tinypico.com",
   "vendor": "TinyPICO"
diff --git a/boards/ttgo-t1.json b/boards/ttgo-t1.json
index b14e61b..b8c6e7f 100644
--- a/boards/ttgo-t1.json
+++ b/boards/ttgo-t1.json
@@ -25,7 +25,7 @@
     "maximum_ram_size": 327680,
     "maximum_size": 4194304,
     "require_upload_port": true,
-    "speed": 921600
+    "speed": 460800
   },
   "url": "https://github.com/LilyGO/ESP32-TTGO-T1",
   "vendor": "TTGO"
diff --git a/boards/wemos_d1_mini32.json b/boards/wemos_d1_mini32.json
index 2d2c54e..82b9cb7 100644
--- a/boards/wemos_d1_mini32.json
+++ b/boards/wemos_d1_mini32.json
@@ -28,7 +28,7 @@
     "maximum_ram_size": 327680,
     "maximum_size": 4194304,
     "require_upload_port": true,
-    "speed": 921600
+    "speed": 460800
   },
   "url": "https://www.wemos.cc",
   "vendor": "WEMOS"