diff --git a/ports/atmel-samd/boards/arduino_mkr1300/mpconfigboard.mk b/ports/atmel-samd/boards/arduino_mkr1300/mpconfigboard.mk
index abbdbe87ef..c3d75202bf 100644
--- a/ports/atmel-samd/boards/arduino_mkr1300/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/arduino_mkr1300/mpconfigboard.mk
@@ -9,5 +9,3 @@ CHIP_FAMILY = samd21
 INTERNAL_FLASH_FILESYSTEM = 1
 LONGINT_IMPL = NONE
 CIRCUITPY_FULL_BUILD = 0
-
-CIRCUITPY_RAINBOWIO = 0
diff --git a/ports/atmel-samd/boards/arduino_nano_33_iot/mpconfigboard.mk b/ports/atmel-samd/boards/arduino_nano_33_iot/mpconfigboard.mk
index 38b1e96d6b..895c027ee5 100644
--- a/ports/atmel-samd/boards/arduino_nano_33_iot/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/arduino_nano_33_iot/mpconfigboard.mk
@@ -9,6 +9,3 @@ CHIP_FAMILY = samd21
 INTERNAL_FLASH_FILESYSTEM = 1
 LONGINT_IMPL = NONE
 CIRCUITPY_FULL_BUILD = 0
-
-# This board has many pins, and we have to remove something else to make room.
-CIRCUITPY_RAINBOWIO = 0
diff --git a/ports/atmel-samd/boards/arduino_zero/mpconfigboard.mk b/ports/atmel-samd/boards/arduino_zero/mpconfigboard.mk
index 5d0734f69d..f1c3631dcb 100644
--- a/ports/atmel-samd/boards/arduino_zero/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/arduino_zero/mpconfigboard.mk
@@ -11,4 +11,3 @@ LONGINT_IMPL = NONE
 CIRCUITPY_FULL_BUILD = 0
 
 CIRCUITPY_ONEWIREIO = 0
-CIRCUITPY_RAINBOWIO = 0
diff --git a/ports/atmel-samd/boards/sensebox_mcu/mpconfigboard.mk b/ports/atmel-samd/boards/sensebox_mcu/mpconfigboard.mk
index ea14f63ad9..0fc15cb321 100644
--- a/ports/atmel-samd/boards/sensebox_mcu/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/sensebox_mcu/mpconfigboard.mk
@@ -12,5 +12,4 @@ CIRCUITPY_FULL_BUILD = 0
 
 # There are many pin definitions on this board; it doesn't quite fit on very large translations.
 CIRCUITPY_ONEWIREIO = 0
-CIRCUITPY_RAINBOWIO = 0
 CIRCUITPY_USB_MIDI = 0