diff --git a/lib/misc/allowed_chars.txt b/lib/misc/allowed_chars.txt
new file mode 100644
index 0000000..e3f4880
--- /dev/null
+++ b/lib/misc/allowed_chars.txt
@@ -0,0 +1 @@
+abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789ÄÖÜäöüß&*$% ':?,-(+.)/
diff --git a/lib/sepa_king/converter.rb b/lib/sepa_king/converter.rb
index 4141964..9f345d3 100644
--- a/lib/sepa_king/converter.rb
+++ b/lib/sepa_king/converter.rb
@@ -15,6 +15,8 @@ def convert(*attributes, options)
     end
 
     module InstanceMethods
+      ALLOWED_CHARS = Regexp.escape(File.read('lib/misc/allowed_chars.txt')).freeze
+
       def convert_text(value)
         return unless value
 
@@ -29,7 +31,7 @@ def convert_text(value)
           gsub(/\n+/,' ').
 
           # Remove all invalid characters
-          gsub(/[^a-zA-Z0-9ÄÖÜäöüß&*$%\ \'\:\?\,\-\(\+\.\)\/]/, '').
+          gsub(/[^#{ALLOWED_CHARS}]/, '').
 
           # Remove leading and trailing spaces
           strip