diff --git a/buildroot/share/PlatformIO/scripts/SAMD51_grandcentral_m4.py b/buildroot/share/PlatformIO/scripts/SAMD51_grandcentral_m4.py
new file mode 100644
index 0000000000..05dc444bda
--- /dev/null
+++ b/buildroot/share/PlatformIO/scripts/SAMD51_grandcentral_m4.py
@@ -0,0 +1,18 @@
+#
+# SAMD51_grandcentral_m4.py
+# Customizations for env:SAMD51_grandcentral_m4
+#
+from os.path import join, isfile
+import shutil
+from pprint import pprint
+
+Import("env")
+
+rxBuf = env["MARLIN_FEATURES"]["RX_BUFFER_SIZE"] if "RX_BUFFER_SIZE" in env["MARLIN_FEATURES"] else "0"
+txBuf = env["MARLIN_FEATURES"]["TX_BUFFER_SIZE"] if "TX_BUFFER_SIZE" in env["MARLIN_FEATURES"] else "0"
+
+serialBuf = str(max(int(rxBuf), int(txBuf), 350))
+
+build_flags = env.get('BUILD_FLAGS')
+build_flags.append("-DSERIAL_BUFFER_SIZE=" + serialBuf)
+env.Replace(BUILD_FLAGS=build_flags)
diff --git a/platformio.ini b/platformio.ini
index 7ddd832f8e..157b3d6201 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -681,6 +681,8 @@ src_filter     = ${common.default_src_filter} +<src/HAL/SAMD51>
 lib_deps       = ${common.lib_deps}
   SoftwareSerialM
   Adafruit SPIFlash
+extra_scripts  = ${common.extra_scripts}
+  pre:buildroot/share/PlatformIO/scripts/SAMD51_grandcentral_m4.py
 custom_marlin.SDSUPPORT = SdFat - Adafruit Fork
 debug_tool     = jlink