diff --git a/ports/nrf/Makefile b/ports/nrf/Makefile
index bd177108e..2a80ee58e 100644
--- a/ports/nrf/Makefile
+++ b/ports/nrf/Makefile
@@ -128,6 +128,9 @@ CFLAGS += -Os -DNDEBUG
 LDFLAGS += -Os
 endif
 
+# Options for mpy-cross
+MPY_CROSS_FLAGS += -march=armv7m
+
 LIBS = \
 
 ifeq ($(MCU_VARIANT), nrf52)