diff --git a/ports/bare-arm/Makefile b/ports/bare-arm/Makefile
index 0fcd5d0272..a515db80e0 100644
--- a/ports/bare-arm/Makefile
+++ b/ports/bare-arm/Makefile
@@ -36,7 +36,7 @@ SRC_S = \
 #	startup_stm32f40xx.s \
 	gchelper.s \
 
-OBJ = $(PY_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o) $(SRC_S:.s=.o))
+OBJ = $(PY_CORE_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o) $(SRC_S:.s=.o))
 
 all: $(BUILD)/firmware.elf
 
diff --git a/ports/minimal/Makefile b/ports/minimal/Makefile
index ae295d655e..e97fb16d8d 100644
--- a/ports/minimal/Makefile
+++ b/ports/minimal/Makefile
@@ -47,7 +47,7 @@ SRC_C = \
 	lib/mp-readline/readline.c \
 	$(BUILD)/_frozen_mpy.c \
 
-OBJ = $(PY_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
+OBJ = $(PY_CORE_O) $(addprefix $(BUILD)/, $(SRC_C:.c=.o))
 
 ifeq ($(CROSS), 1)
 all: $(BUILD)/firmware.dfu