@@ -15,7 +15,7 @@ LC_ALL=C

 export LC_ALL

 # Make tracing more educational

-export PS4='+ ${BASH_SOURCE}:${FUNCNAME[0]}:L${LINENO}:   '

+export PS4='+ ${BASH_SOURCE:-}:${FUNCNAME[0]:-}:L${LINENO:-}:   '

 # Find the other rc files

 RC_DIR=$(cd $(dirname "${BASH_SOURCE:-$0}") && pwd)