diff --git a/ports/qemu-arm/Makefile b/ports/qemu-arm/Makefile
index c730c82975..92574d0e11 100644
--- a/ports/qemu-arm/Makefile
+++ b/ports/qemu-arm/Makefile
@@ -114,11 +114,10 @@ OBJ = $(OBJ_COMMON) $(OBJ_RUN) $(OBJ_TEST)
 # List of sources for qstr extraction
 SRC_QSTR += $(SRC_COMMON_C) $(SRC_RUN_C) $(LIB_SRC_C)
 
-ifneq ($(FROZEN_MPY_DIR),)
-# To use frozen bytecode, put your .py files in a subdirectory (eg frozen/) and
-# then invoke make with FROZEN_MPY_DIR=frozen (be sure to build from scratch).
-CFLAGS += -DMICROPY_QSTR_EXTRA_POOL=mp_qstr_frozen_const_pool
+ifneq ($(FROZEN_MANIFEST),)
+CFLAGS += -DMICROPY_MODULE_FROZEN_STR
 CFLAGS += -DMICROPY_MODULE_FROZEN_MPY
+CFLAGS += -DMICROPY_QSTR_EXTRA_POOL=mp_qstr_frozen_const_pool
 MPY_CROSS_FLAGS += -march=armv7m
 endif
 
diff --git a/ports/qemu-arm/Makefile.test b/ports/qemu-arm/Makefile.test
index 32ec95a4f3..4204a84f0d 100644
--- a/ports/qemu-arm/Makefile.test
+++ b/ports/qemu-arm/Makefile.test
@@ -1,6 +1,6 @@
 LIB_SRC_C = lib/upytesthelper/upytesthelper.c
 
-FROZEN_MPY_DIR ?= test-frzmpy
+FROZEN_MANIFEST ?= "freeze('test-frzmpy')"
 
 include Makefile