diff --git a/flask_debugtoolbar/__init__.py b/flask_debugtoolbar/__init__.py
index 308f590..9a1cfad 100644
--- a/flask_debugtoolbar/__init__.py
+++ b/flask_debugtoolbar/__init__.py
@@ -8,6 +8,7 @@ from werkzeug.exceptions import HTTPException
 from werkzeug.urls import url_quote_plus
 
 from flask_debugtoolbar.toolbar import DebugToolbar
+from flask_debugtoolbar.compat import iteritems
 from flask import Blueprint
 
 
@@ -27,13 +28,9 @@ def replace_insensitive(string, target, replacement):
 
 
 def _printable(value):
-    if isinstance(value, unicode):
-        return value.encode('unicode_escape')
-    elif isinstance(value, str):
-        return value.encode('string_escape')
     try:
         return repr(value)
-    except Exception, e:
+    except Exception as e:
         return '<repr(%s) raised %s: %s>' % (
                object.__repr__(value), type(e).__name__, e)
 
@@ -61,7 +58,7 @@ class DebugToolbarExtension(object):
             self.init_app(app)
 
     def init_app(self, app):
-        for k, v in self._default_config(app).iteritems():
+        for k, v in iteritems(self._default_config(app)):
             app.config.setdefault(k, v)
 
         if not app.config['DEBUG_TB_ENABLED']:
diff --git a/flask_debugtoolbar/compat.py b/flask_debugtoolbar/compat.py
new file mode 100644
index 0000000..7db9953
--- /dev/null
+++ b/flask_debugtoolbar/compat.py
@@ -0,0 +1,9 @@
+import sys
+
+PY2 = sys.version_info[0] == 2
+
+
+if PY2:
+    iteritems = lambda d: d.iteritems()
+else:
+    iteritems = lambda d: iter(d.items())
\ No newline at end of file
diff --git a/flask_debugtoolbar/templates/panels/headers.html b/flask_debugtoolbar/templates/panels/headers.html
index 2a1486c..2155ce5 100644
--- a/flask_debugtoolbar/templates/panels/headers.html
+++ b/flask_debugtoolbar/templates/panels/headers.html
@@ -6,7 +6,7 @@
     </tr>
   </thead>
   <tbody>
-    {% for key, value in headers.iteritems() %}
+    {% for key, value in headers|dictsort %}
       <tr class="{{ loop.cycle('flDebugOdd', 'flDebugEven') }}">
         <td>{{ key|escape }}</td>
         <td>{{ value|escape }}</td>
diff --git a/flask_debugtoolbar/toolbar.py b/flask_debugtoolbar/toolbar.py
index 74e92dc..0d3a7aa 100644
--- a/flask_debugtoolbar/toolbar.py
+++ b/flask_debugtoolbar/toolbar.py
@@ -1,4 +1,7 @@
-import urllib
+try:
+    from urllib.parse import unquote
+except ImportError:
+    from urllib import unquote
 
 from flask import url_for, current_app
 from werkzeug.utils import import_string
@@ -24,7 +27,7 @@ class DebugToolbar(object):
         Populate debug panels
         """
         activated = self.request.cookies.get('fldt_active', '')
-        activated = urllib.unquote(activated).split(';')
+        activated = unquote(activated).split(';')
 
         for panel_path in current_app.config['DEBUG_TB_PANELS']:
             panel_class = self._import_panel(panel_path)
@@ -54,7 +57,7 @@ class DebugToolbar(object):
 
         try:
             panel_class = import_string(path)
-        except ImportError, e:
+        except ImportError as e:
             current_app.logger.warning('Disabled %s due to ImportError: %s', path, e)
             panel_class = None