diff --git a/init_hdl.sh b/init_hdl.sh
index fc129403f130e8db1f0bf63f010fa97f247bde5f..42eeaaab84b5baf6d436e9612c7e9033a8fe730e 100644
--- a/init_hdl.sh
+++ b/init_hdl.sh
@@ -41,6 +41,13 @@ export RADIOHDL_WORK="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
 export HDL_BUILD_DIR=${HDL_BUILD_DIR:-${RADIOHDL_WORK}/build}
 echo "HDL environment will be setup for" $RADIOHDL_WORK
 
+# modelsim uses this sim dir for testing
+export HDL_IOFILE_SIM_DIR=${HDL_IOFILE_SIM_DIR:-${HDL_BUILD_DIR}/sim}
+if ! [[ -e HDL_IOFILE_SIM_DIR ]]; then
+    echo "make sim dir"
+    mkdir ${HDL_BUILD_DIR}/sim
+fi
+rm -r ${HDL_BUILD_DIR}/sim/*
 
 # copy git user_componets.ipx into Altera dir's
 for altera_dir in ${ALTERA_DIR}/*; do
@@ -50,11 +57,6 @@ for altera_dir in ${ALTERA_DIR}/*; do
     fi
 done
 
-
 if [ -z "${RADIOHDL_GEAR}" ]; then
     . ../radiohdl/init_radiohdl.sh
 fi
-
-if [ -z "${UPE_GEAR}" ]; then
-    . ../upe_gear/init_upe.sh
-fi