diff --git a/ports/samd/mcu/samd21/mpconfigmcu.h b/ports/samd/mcu/samd21/mpconfigmcu.h
index e0af60552b02..8d155f93ab03 100644
--- a/ports/samd/mcu/samd21/mpconfigmcu.h
+++ b/ports/samd/mcu/samd21/mpconfigmcu.h
@@ -9,13 +9,24 @@
 #define MICROPY_MODULE_BUILTIN_INIT     (1)
 
 #define MICROPY_FLOAT_IMPL              (MICROPY_FLOAT_IMPL_FLOAT)
+
+#ifndef MICROPY_PY_BUILTINS_COMPLEX
 #define MICROPY_PY_BUILTINS_COMPLEX     (0)
-#define MICROPY_PY_MATH                 (0)
+#endif
+
+#ifndef MICROPY_PY_MATH
+#define MICROPY_PY_MATH                 (1)
+#endif
+
+#ifndef MICROPY_PY_CMATH
 #define MICROPY_PY_CMATH                (0)
+#endif
 
 #define VFS_BLOCK_SIZE_BYTES            (1536) // 24x 64B flash pages;
 
+#ifndef MICROPY_HW_UART_TXBUF
 #define MICROPY_HW_UART_TXBUF           (1)
+#endif
 
 #define CPU_FREQ                        (48000000)
 #define DFLL48M_FREQ                    (48000000)
diff --git a/ports/samd/mcu/samd21/mpconfigmcu.mk b/ports/samd/mcu/samd21/mpconfigmcu.mk
index cc435da8cc91..287d6d18be7b 100644
--- a/ports/samd/mcu/samd21/mpconfigmcu.mk
+++ b/ports/samd/mcu/samd21/mpconfigmcu.mk
@@ -1 +1,30 @@
 SRC_S += shared/runtime/gchelper_m0.s
+
+LIBM_SRC_C +=  $(addprefix lib/libm/,\
+	acoshf.c \
+	asinfacosf.c \
+	asinhf.c \
+	atan2f.c \
+	atanf.c \
+	atanhf.c \
+	ef_rem_pio2.c \
+	erf_lgamma.c \
+	fmodf.c \
+	kf_cos.c \
+	kf_rem_pio2.c \
+	kf_sin.c \
+	kf_tan.c \
+	log1pf.c \
+	math.c \
+	nearbyintf.c \
+	roundf.c \
+	sf_cos.c \
+	sf_erf.c \
+	sf_frexp.c \
+	sf_ldexp.c \
+	sf_modf.c \
+	sf_sin.c \
+	sf_tan.c \
+	wf_lgamma.c \
+	wf_tgamma.c \
+	)
diff --git a/ports/samd/mcu/samd51/mpconfigmcu.h b/ports/samd/mcu/samd51/mpconfigmcu.h
index 686cfd6104df..666370c983b7 100644
--- a/ports/samd/mcu/samd51/mpconfigmcu.h
+++ b/ports/samd/mcu/samd51/mpconfigmcu.h
@@ -8,10 +8,19 @@
 #define MICROPY_EMIT_INLINE_THUMB       (1)
 
 #define MICROPY_FLOAT_IMPL              (MICROPY_FLOAT_IMPL_FLOAT)
+
+#ifndef MICROPY_PY_BUILTINS_COMPLEX
 #define MICROPY_PY_BUILTINS_COMPLEX     (0)
+#endif
+
+#ifndef MICROPY_PY_MATH
 #define MICROPY_PY_MATH                 (1)
 #define MP_NEED_LOG2                    (1)
+#endif
+
+#ifndef MICROPY_PY_CMATH
 #define MICROPY_PY_CMATH                (0)
+#endif
 
 #define MICROPY_PY_MACHINE_DHT_READINTO (1)
 #define MICROPY_PY_ONEWIRE              (1)
@@ -30,7 +39,9 @@ unsigned long trng_random_u32(void);
 
 #define VFS_BLOCK_SIZE_BYTES            (1536) //
 
+#ifndef MICROPY_HW_UART_TXBUF
 #define MICROPY_HW_UART_TXBUF           (1)
+#endif
 
 #define CPU_FREQ                        (120000000)
 #define DFLL48M_FREQ                    (48000000)