diff --git a/completions/isql b/completions/isql
index 496e8529fee..c6fe7abf768 100644
--- a/completions/isql
+++ b/completions/isql
@@ -6,7 +6,7 @@ _comp_cmd_isql()
     local cur prev words cword comp_args
     _comp_initialize -- "$@" || return
 
-    [[ -f $ODBCINI ]] &&
+    [[ -f ${ODBCINI-} ]] &&
         COMPREPLY=($(command grep "\[$cur" "$ODBCINI" | tr -d \[\]))
 } &&
     complete -F _comp_cmd_isql isql