diff --git a/ports/esp32/Makefile b/ports/esp32/Makefile
index ce574ce799..3df2af4716 100644
--- a/ports/esp32/Makefile
+++ b/ports/esp32/Makefile
@@ -42,7 +42,7 @@ ifdef USER_C_MODULES
 	CMAKE_ARGS += -DUSER_C_MODULES=${USER_C_MODULES}
 endif
 
-IDFPY_FLAGS += -D MICROPY_BOARD=$(BOARD) -D MICROPY_BOARD_DIR=$(abspath $(BOARD_DIR)) $(CMAKE_ARGS)
+IDFPY_FLAGS += -D MICROPY_BOARD=$(BOARD) -D MICROPY_BOARD_DIR="$(abspath $(BOARD_DIR))" $(CMAKE_ARGS)
 
 ifdef FROZEN_MANIFEST
        IDFPY_FLAGS += -D MICROPY_FROZEN_MANIFEST=$(FROZEN_MANIFEST)
diff --git a/ports/mimxrt/Makefile b/ports/mimxrt/Makefile
index f514b773fd..dd1f5aa7c6 100644
--- a/ports/mimxrt/Makefile
+++ b/ports/mimxrt/Makefile
@@ -491,7 +491,7 @@ $(GEN_FLEXRAM_CONFIG_SRC):
 $(BUILD)/%_gen.c $(HEADER_BUILD)/%.h: $(BOARD_PINS) $(MAKE_PINS) $(AF_FILE) $(PREFIX_FILE) | $(HEADER_BUILD)
 	$(ECHO) "Create $@"
 	$(Q)$(PYTHON) $(MAKE_PINS) --board-csv $(BOARD_PINS) --af-csv $(AF_FILE) \
-	    --prefix $(PREFIX_FILE) --iomux $(abspath $(TOP)/$(MCU_DIR)/drivers/fsl_iomuxc.h) \
+	    --prefix $(PREFIX_FILE) --iomux "$(abspath $(TOP)/$(MCU_DIR)/drivers/fsl_iomuxc.h)" \
 	    --output-source $(GEN_PINS_SRC) --output-header $(GEN_PINS_HDR)
 
 include $(TOP)/py/mkrules.mk
diff --git a/ports/rp2/Makefile b/ports/rp2/Makefile
index 11d2115a2f..b6e8852169 100644
--- a/ports/rp2/Makefile
+++ b/ports/rp2/Makefile
@@ -30,7 +30,7 @@ endif
 
 $(VERBOSE)MAKESILENT = -s
 
-CMAKE_ARGS = -DMICROPY_BOARD=$(BOARD) -DMICROPY_BOARD_DIR=$(abspath $(BOARD_DIR))
+CMAKE_ARGS = -DMICROPY_BOARD=$(BOARD) -DMICROPY_BOARD_DIR="$(abspath $(BOARD_DIR))"
 
 ifdef USER_C_MODULES
 CMAKE_ARGS += -DUSER_C_MODULES=${USER_C_MODULES}
diff --git a/ports/stm32/mboot/Makefile b/ports/stm32/mboot/Makefile
index 389f9f5d0f..9908194237 100755
--- a/ports/stm32/mboot/Makefile
+++ b/ports/stm32/mboot/Makefile
@@ -6,7 +6,7 @@ BOARD ?= $(notdir $(BOARD_DIR:/=))
 else
 # If not given on the command line, then default to PYBV10.
 BOARD ?= PYBV10
-BOARD_DIR ?= $(abspath ../boards/$(BOARD))
+BOARD_DIR ?= ../boards/$(BOARD)
 endif
 
 # If the build directory is not given, make it reflect the board name.
diff --git a/py/mkrules.mk b/py/mkrules.mk
index 30483feb5c..5050935873 100644
--- a/py/mkrules.mk
+++ b/py/mkrules.mk
@@ -176,7 +176,7 @@ $(HEADER_BUILD):
 ifneq ($(MICROPY_MPYCROSS_DEPENDENCY),)
 # to automatically build mpy-cross, if needed
 $(MICROPY_MPYCROSS_DEPENDENCY):
-	$(MAKE) -C $(abspath $(dir $@)..)
+	$(MAKE) -C "$(abspath $(dir $@)..)"
 endif
 
 ifneq ($(FROZEN_DIR),)