diff --git a/firanka/series/base.py b/firanka/series/base.py
index a67bef93320aa59dacb3514a2830feea604ad1a9..1c0fcee844d08a1682e704538bfdb1e791ca6df3 100644
--- a/firanka/series/base.py
+++ b/firanka/series/base.py
@@ -5,6 +5,7 @@ import six
 
 from firanka.exceptions import NotInDomainError
 from firanka.ranges import Range, EMPTY_SET
+from sortedcontainers import SortedList
 
 
 class Series(object):
@@ -117,6 +118,9 @@ class Series(object):
 
 class DiscreteSeries(Series):
     def __init__(self, data, domain=None, *args, **kwargs):
+
+        data = SortedList(data)
+
         if len(data) == 0:
             domain = EMPTY_SET
         elif domain is None:
diff --git a/requirements.txt b/requirements.txt
index ffe2fce498955b628014618b28c6bcf152466a4a..72f6bbc17f3036067e5c55944aa0bebee4b9fc22 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1 +1,2 @@
 six
+sortedcontainers
diff --git a/setup.cfg b/setup.cfg
index f5a5bacec769d8a50d08cab9fe7de7498a9a9e78..14f1325337f48234d936a2f79166d5df4492c35e 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -20,7 +20,7 @@ author_email = piotrm@dms-serwis.pl
 url = https://github.com/smok-serwis/firanka
 
 [pycodestyle]
-max-line-length=80
+max-line-length=100
 
 [bdist_wheel]
 universal=1