diff --git a/exercises/UNIX_HPC_exercise_instructions.md b/exercises/UNIX_HPC_exercise_instructions.md
index 97906eed48a0b443dfdc82a44f2a43096db3a70b..3fa98be40e142861527c4d13d77b3905f28b8d87 100644
--- a/exercises/UNIX_HPC_exercise_instructions.md
+++ b/exercises/UNIX_HPC_exercise_instructions.md
@@ -438,7 +438,7 @@
 Please run the following commands (copy and paste to your command line):
 ```sh
 mkdir /home/$USER/scratch/singularity_tmpdir
-echo "export SINGULARITY_TMPDIR=/home/$USER/scratch/singularity_tmpdir" >> $HOME/.bashrc
+echo "export TMPDIR=/home/$USER/scratch/singularity_tmpdir" >> $HOME/.bashrc
 echo "export SINGULARITY_BINDPATH=/scratch,/data,/home/$USER,/shares/amr.imm.uzh" >> $HOME/.bashrc
 source $HOME/.bashrc
 ```