diff --git a/chartkick/ext.py b/chartkick/ext.py
index 4feea9a..95367cd 100644
--- a/chartkick/ext.py
+++ b/chartkick/ext.py
@@ -5,6 +5,7 @@
 import json
 import itertools
 import functools
+from distutils.version import LooseVersion
 
 import jinja2
 from jinja2 import nodes
@@ -67,11 +68,7 @@ def _chart_support(self, name, data, caller, **kwargs):
         options = dict(self.environment.options)
         options.update(name=name, id=id)
 
-        # jinja2 prepends 'l_' or 'l_{{ n }}'(ver>=2.9) to keys
-        if jinja2.__version__ >= '2.9':
-            kwargs = dict((k[4:], v) for (k, v) in kwargs.items())
-        else:
-            kwargs = dict((k[2:], v) for (k, v) in kwargs.items())
+        kwargs = dict((k[4:], v) for (k, v) in kwargs.items())
 
         if self._library is None:
             self._library = self.load_library()
diff --git a/chartkick/js/chartkick.js b/chartkick/js/chartkick.js
index 474ee4c..48deafd 100644
--- a/chartkick/js/chartkick.js
+++ b/chartkick/js/chartkick.js
@@ -1273,11 +1273,9 @@
                 options.scales.xAxes[0].time.unit = "day";
                 step = 1;
               } else if (hour || timeDiff > 0.5) {
-                options.scales.xAxes[0].time.displayFormats = {hour: "MMM D, h a"};
                 options.scales.xAxes[0].time.unit = "hour";
                 step = 1 / 24.0;
               } else if (minute) {
-                options.scales.xAxes[0].time.displayFormats = {minute: "h:mm a"};
                 options.scales.xAxes[0].time.unit = "minute";
                 step = 1 / 24.0 / 60.0;
               }