diff --git a/back_pwquality.sh b/back_pwquality.sh
index 29e27a7..a054657 100644
--- a/back_pwquality.sh
+++ b/back_pwquality.sh
@@ -27,9 +27,15 @@ _mk_pwquality_conf() {
 	while [ -n "$1" ]; do
 		case "$1" in
 			--difok) shift;
-				 _check_argument "$1" "--difok"
-				 ;;
-			--minlen)
+				 _check_argument_is_number "$1" "--difok"
+		;;
+			--minlen) shift;
+				  _check_argument_value "$1" "6" "--minlen"
+		;;
+			--dcredit) shift;
+				   _check_argument_is_number "$1" "--dcredit" "-"		   
+		;;
 		 esac
 	 done
- }
+}
+_mk_pwquality_conf --dcredit -1
diff --git a/common.sh b/common.sh
index 092b1c9..75a0535 100644
--- a/common.sh
+++ b/common.sh
@@ -17,6 +17,9 @@ _check_argument_is_number() {
 	if [[ "$1" == [0-9]* ]]; then
 		return 0
 	else
+		if [ -n "$3" ]; then
+			grep -Exq -- "(\-|\+)[0-9]*" <<< "$1" && return 0
+		fi
 		error $"Argument to %s must be a number" "$2"
 		return 1
 	fi