diff --git a/scripts/make_tb_path.mk b/scripts/make_tb_path.mk
index 9f0c5fe4..c1d3707b 100644
--- a/scripts/make_tb_path.mk
+++ b/scripts/make_tb_path.mk
@@ -2,8 +2,14 @@
 ####################################################################################
 ####################################################################################
 
+ifeq ($(ADI_HDL_DIR),)
+$(error Environment variable ADI_HDL_DIR not set, please set it with the absolute path to the hdl repository.)
+endif
+
+ifeq ($(ADI_TB_DIR),)
+$(error Environment variable ADI_TB_DIR not set, please set it with the absolute path to the testbenches repository.)
+endif
+
 # Assumes this file is in <HDL>/testbenches/scripts/make_tb_path.mk
-ADI_HDL_DIR := ${ADI_HDL_DIR}
 HDL_LIBRARY_PATH := $(ADI_HDL_DIR)/library/
-ADI_TB_DIR := ${ADI_TB_DIR}
 TB_LIBRARY_PATH := $(ADI_TB_DIR)/library/