diff --git a/ports/atmel-samd/boards/arduino_mkr1300/mpconfigboard.mk b/ports/atmel-samd/boards/arduino_mkr1300/mpconfigboard.mk
index c3d75202bf..abbdbe87ef 100644
--- a/ports/atmel-samd/boards/arduino_mkr1300/mpconfigboard.mk
+++ b/ports/atmel-samd/boards/arduino_mkr1300/mpconfigboard.mk
@@ -9,3 +9,5 @@ CHIP_FAMILY = samd21
 INTERNAL_FLASH_FILESYSTEM = 1
 LONGINT_IMPL = NONE
 CIRCUITPY_FULL_BUILD = 0
+
+CIRCUITPY_RAINBOWIO = 0
diff --git a/py/circuitpy_mpconfig.h b/py/circuitpy_mpconfig.h
index 03dca0321c..1c4430525e 100644
--- a/py/circuitpy_mpconfig.h
+++ b/py/circuitpy_mpconfig.h
@@ -213,7 +213,7 @@ typedef long mp_off_t;
 #define MICROPY_CPYTHON_COMPAT                (CIRCUITPY_FULL_BUILD)
 #endif
 #define MICROPY_PY_BUILTINS_POW3              (CIRCUITPY_BUILTINS_POW3)
-#define MICROPY_PY_FSTRINGS                   (MICROPY_CPYTHON_COMPAT)
+#define MICROPY_PY_FSTRINGS                   (1)
 #define MICROPY_MODULE_WEAK_LINKS             (0)
 #define MICROPY_PY_ALL_SPECIAL_METHODS        (CIRCUITPY_FULL_BUILD)
 #ifndef MICROPY_PY_BUILTINS_COMPLEX