diff --git a/nersc/setup_td_dev.sh b/nersc/setup_td_dev.sh
index 3e1f07a..61188d9 100755
--- a/nersc/setup_td_dev.sh
+++ b/nersc/setup_td_dev.sh
@@ -119,6 +119,7 @@ then
     
   export GSL_DIR=$DESC_TD_INSTALL/conda/envs/$LSST_CONDA_ENV_NAME
   export CFITSIO_DIR=$DESC_TD_INSTALL/conda/envs/$LSST_CONDA_ENV_NAME
+  export ROOT_DIR=$ROOTSYS
 
   export PYTHONPATH=$PYTHONPATH:$DESC_TD_INSTALL