diff --git a/helpers/arg-parser/args.sh b/helpers/arg-parser/args.sh
index 5d59b65..79a12dd 100755
--- a/helpers/arg-parser/args.sh
+++ b/helpers/arg-parser/args.sh
@@ -41,7 +41,9 @@ arg() {
         grep_match "$arg_search" "^(\w|--)" && continue
 
         # clear $arg_search from special and duplicate characters, e.g. 'fas-)dfs' will become 'fasd'
-        local arg_chars="$(printf "%s" "$arg_search" | tr -s [$arg_search] | tr -d "[:punct:][:blank:]")"
+        local arg_chars="$(printf "%s" "$arg_search" \
+            | tr -s "[$arg_search]" 2>&1 >/dev/null \
+            | tr -d "[:punct:][:blank:]" 2>&1 >/dev/null)"
 
         # if $arg_name is not one of $arg_chars the skip it
         grep_match "-$arg_name" "^-[$arg_chars]$" || continue