--- alexandria-book-collection-manager-0.7.4/lib/alexandria/preferences.rb.negative	2019-10-25 01:20:07.000000000 +0900
+++ alexandria-book-collection-manager-0.7.4/lib/alexandria/preferences.rb	2020-01-04 14:09:13.773911633 +0900
@@ -239,7 +239,7 @@ module Alexandria
         true
       elsif value == "false"    # bool
         false
-      elsif /^[0-9]+$/.match?(value) # int
+      elsif /^-?[0-9]+$/.match?(value) # int
         value.to_i
       elsif value =~ /^\[(.*)\]$/ # list (assume of type String)
         Regexp.last_match[1].split(",")