diff --git a/init_hdl.sh b/init_hdl.sh
index 0231de181211e40e93643a5bb28c3f6b968984c1..8dfeb67292e7e6c6ddd95e950575a31ab534ffc3 100644
--- a/init_hdl.sh
+++ b/init_hdl.sh
@@ -47,11 +47,11 @@ export RADIOHDL_WORK="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 echo "HDL environment will be setup for" $RADIOHDL_WORK
 
 # setup paths to build and config dir if not already defined by the user.
-export ARGS_WORK=${ARGS_WORK:-${RADIOHDL_WORK}}
-export RADIOHDL_BUILD_DIR=${RADIOHDL_BUILD_DIR:-${RADIOHDL_WORK}/build}
+export ARGS_WORK=${RADIOHDL_WORK}
+export RADIOHDL_BUILD_DIR=${RADIOHDL_WORK}/build
 
 # modelsim uses this sim dir for testing
-export HDL_IOFILE_SIM_DIR=${HDL_IOFILE_SIM_DIR:-${RADIOHDL_BUILD_DIR}/sim}
+export HDL_IOFILE_SIM_DIR=${RADIOHDL_BUILD_DIR}/sim
 if [[ ! -d "${HDL_IOFILE_SIM_DIR}" ]]; then
     echo "make sim dir"
     mkdir "${HDL_IOFILE_SIM_DIR}"