diff --git a/py/builtinhelp.c b/py/builtinhelp.c
index 453c9bb118..7411c57aae 100644
--- a/py/builtinhelp.c
+++ b/py/builtinhelp.c
@@ -79,12 +79,8 @@ STATIC void mp_help_add_from_names(mp_obj_t list, const char *name) {
 
 // These externs were originally declared inside mp_help_print_modules(),
 // but they triggered -Wnested-externs, so they were moved outside.
-#if MICROPY_MODULE_FROZEN_STR
-extern const char mp_frozen_str_names[];
-#endif
-
-#if MICROPY_MODULE_FROZEN_MPY
-extern const char mp_frozen_mpy_names[];
+#if MICROPY_MODULE_FROZEN
+extern const char mp_frozen_names[];
 #endif
 
 STATIC void mp_help_print_modules(void) {
@@ -93,7 +89,6 @@ STATIC void mp_help_print_modules(void) {
     mp_help_add_from_map(list, &mp_builtin_module_map);
 
     #if MICROPY_MODULE_FROZEN
-    extern const char mp_frozen_names[];
     mp_help_add_from_names(list, mp_frozen_names);
     #endif
 
diff --git a/py/circuitpy_mpconfig.mk b/py/circuitpy_mpconfig.mk
index 14852580e5..42f7d29f33 100644
--- a/py/circuitpy_mpconfig.mk
+++ b/py/circuitpy_mpconfig.mk
@@ -489,6 +489,7 @@ CFLAGS += -DLONGINT_IMPL_LONGLONG
 else
 $(error LONGINT_IMPL set to surprising value: "$(LONGINT_IMPL)")
 endif
+MPY_TOOL_FLAGS += $(MPY_TOOL_LONGINT_IMPL)
 
 ###
 ifeq ($(LONGINT_IMPL),NONE)
@@ -497,3 +498,16 @@ else ifeq ($(LONGINT_IMPL),LONGLONG)
 else
 $(error LONGINT_IMPL set to surprising value: "$(LONGINT_IMPL)")
 endif
+
+PREPROCESS_FROZEN_MODULES = PYTHONPATH=$(TOP)/tools/python-semver $(TOP)/tools/preprocess_frozen_modules.py
+ifneq ($(FROZEN_MPY_DIRS),)
+$(BUILD)/frozen_mpy: $(FROZEN_MPY_DIRS)
+	$(ECHO) FREEZE $(FROZEN_MPY_DIRS)
+	$(Q)$(MKDIR) -p $@
+	$(Q)$(PREPROCESS_FROZEN_MODULES) -o $@ $(FROZEN_MPY_DIRS)
+
+$(BUILD)/manifest.py: $(BUILD)/frozen_mpy | $(TOP)/py/circuitpy_mpconfig.mk mpconfigport.mk boards/$(BOARD)/mpconfigboard.mk
+	$(ECHO) MKMANIFEST $(FROZEN_MPY_DIRS)
+	(cd $(BUILD)/frozen_mpy && find * -name \*.py -exec printf 'freeze_as_mpy("frozen_mpy", "%s")\n' {} \; )> $@.tmp && mv -f $@.tmp $@
+FROZEN_MANIFEST=$(BUILD)/manifest.py
+endif
diff --git a/py/mkrules.mk b/py/mkrules.mk
index d306cfabeb..6bef64fd82 100644
--- a/py/mkrules.mk
+++ b/py/mkrules.mk
@@ -135,7 +135,7 @@ endif
 
 ifneq ($(FROZEN_MANIFEST),)
 # to build frozen_content.c from a manifest
-$(BUILD)/frozen_content.c: FORCE $(BUILD)/genhdr/qstrdefs.generated.h | $(MICROPY_MPYCROSS_DEPENDENCY)
+$(BUILD)/frozen_content.c: FORCE $(FROZEN_MANIFEST) $(BUILD)/genhdr/qstrdefs.generated.h | $(MICROPY_MPYCROSS_DEPENDENCY) $(TOP)/tools/makemanifest.py
 	$(Q)$(MAKE_MANIFEST) -o $@ -v "MPY_DIR=$(TOP)" -v "MPY_LIB_DIR=$(MPY_LIB_DIR)" -v "PORT_DIR=$(shell pwd)" -v "BOARD_DIR=$(BOARD_DIR)" -b "$(BUILD)" $(if $(MPY_CROSS_FLAGS),-f"$(MPY_CROSS_FLAGS)",) --mpy-tool-flags="$(MPY_TOOL_FLAGS)" $(FROZEN_MANIFEST)
 endif