diff --git a/ports/stm32/Makefile b/ports/stm32/Makefile
index 07d366bfea..418562f7cb 100644
--- a/ports/stm32/Makefile
+++ b/ports/stm32/Makefile
@@ -164,7 +164,7 @@ LDFLAGS += -L"$(shell dirname $(LIBSTDCPP_FILE_NAME))"
 endif
 
 # Options for mpy-cross
-MPY_CROSS_FLAGS += -march=armv7m
+MPY_CROSS_FLAGS += -march=$(MPY_CROSS_MCU_ARCH_$(MCU_SERIES))
 
 SHARED_SRC_C += $(addprefix shared/,\
 	libc/string0.c \
diff --git a/ports/stm32/stm32.mk b/ports/stm32/stm32.mk
index b4f73a67f3..ae267a5995 100644
--- a/ports/stm32/stm32.mk
+++ b/ports/stm32/stm32.mk
@@ -69,3 +69,15 @@ CFLAGS_MCU_l4 = $(CFLAGS_CORTEX_M) -mtune=cortex-m4 -mcpu=cortex-m4
 CFLAGS_MCU_h7 = $(CFLAGS_CORTEX_M) -mtune=cortex-m7 -mcpu=cortex-m7
 CFLAGS_MCU_wb = $(CFLAGS_CORTEX_M) -mtune=cortex-m4 -mcpu=cortex-m4
 CFLAGS_MCU_wl = $(CFLAGS_CORTEX_M) -mtune=cortex-m4 -mcpu=cortex-m4
+
+MPY_CROSS_MCU_ARCH_f0 = armv6m
+MPY_CROSS_MCU_ARCH_f4 = armv7m
+MPY_CROSS_MCU_ARCH_f7 = armv7m
+MPY_CROSS_MCU_ARCH_g0 = armv6m
+MPY_CROSS_MCU_ARCH_g4 = armv7m
+MPY_CROSS_MCU_ARCH_l0 = armv6m
+MPY_CROSS_MCU_ARCH_l1 = armv7m
+MPY_CROSS_MCU_ARCH_l4 = armv7m
+MPY_CROSS_MCU_ARCH_h7 = armv7m
+MPY_CROSS_MCU_ARCH_wb = armv7m
+MPY_CROSS_MCU_ARCH_wl = armv7m