Update Makefile PDK_PATH
diff --git a/.github/scripts/dv/run-dv-wrapper.sh b/.github/scripts/dv/run-dv-wrapper.sh
index f431eca..e2fa626 100644
--- a/.github/scripts/dv/run-dv-wrapper.sh
+++ b/.github/scripts/dv/run-dv-wrapper.sh
@@ -32,8 +32,8 @@
 
 cd ..
 
-export PDK_PATH=$(pwd)/pdks/sky130A
-if [ ! -d $PDK_PATH ] 
+export PDK_ROOT=$(pwd)/pdks
+if [ ! -d $PDK_ROOT ] 
 then
     echo "Directory /path/to/dir DOES NOT exists." 
     exit 9999 
diff --git a/verilog/dv/mprj_por/Makefile b/verilog/dv/mprj_por/Makefile
index e54380b..242d99c 100644
--- a/verilog/dv/mprj_por/Makefile
+++ b/verilog/dv/mprj_por/Makefile
@@ -14,6 +14,9 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
+## PDK
+PDK_PATH = $(PDK_ROOT)/sky130A
+
 ## Caravel Pointers
 CARAVEL_ROOT ?= ../../../caravel
 CARAVEL_PATH ?= $(CARAVEL_ROOT)
@@ -30,7 +33,6 @@
 ## RISCV GCC 
 GCC_PATH?=/ef/apps/bin
 GCC_PREFIX?=riscv32-unknown-elf
-PDK_PATH?=/ef/tech/SW/sky130A
 
 ## Simulation mode: RTL/GL
 SIM?=RTL
@@ -59,7 +61,7 @@
 %.vcd: %.vvp
 	vvp $<
 
-%.elf: %.c $(CARAVEL_FIRMWARE_PATH)/sections.lds $(CARAVEL_FIRMWARE_PATH)/start.s
+%.elf: %.c $(CARAVEL_FIRMWARE_PATH)/sections.lds $(CARAVEL_FIRMWARE_PATH)/start.s check-env
 	${GCC_PATH}/${GCC_PREFIX}-gcc -I $(CARAVEL_PATH) -march=rv32imc -mabi=ilp32 -Wl,-Bstatic,-T,$(CARAVEL_FIRMWARE_PATH)/sections.lds,--strip-debug -ffreestanding -nostdlib -o $@ $(CARAVEL_FIRMWARE_PATH)/start.s $<
 
 %.hex: %.elf
@@ -70,6 +72,17 @@
 %.bin: %.elf
 	${GCC_PATH}/${GCC_PREFIX}-objcopy -O binary $< /dev/stdout | tail -c +1048577 > $@
 
+check-env:
+ifndef PDK_ROOT
+	$(error PDK_ROOT is undefined, please export it before running make)
+endif
+ifeq (,$(wildcard $(PDK_ROOT)/sky130A))
+	$(error $(PDK_ROOT)/sky130A not found, please install pdk before running make)
+endif
+ifeq (,$(wildcard $(GCC_PATH)/$(GCC_PREFIX)-gcc ))
+	$(error $(GCC_PATH)/$(GCC_PREFIX)-gcc is not found, please export GCC_PATH and GCC_PREFIX before running make)
+endif
+
 # ---- Clean ----
 
 clean: