diff --git a/install.sh b/install.sh
index f4d7103b20d1cf5b40fff25908d567f195274c95..e35400a17f36187bfcec8e0f85b3fb380ddec922 100755
--- a/install.sh
+++ b/install.sh
@@ -280,7 +280,7 @@ fi
 
 export ATHENA_PREFIX=$PREFIX/local
 export SINGULARITY_BINDPATH=$BINDPATH
-$SINGULARITY exec $SIF eic-shell \$@
+\${SINGULARITY:-$SINGULARITY} exec \${SIF:-$SIF} eic-shell \$@
 EOF
 
   chmod +x eic-shell