diff --git a/examples/demo.py b/examples/demo.py
index 5123043..838198f 100755
--- a/examples/demo.py
+++ b/examples/demo.py
@@ -77,7 +77,7 @@ class MyLine(Line):
     """
 
     def __init__(self):
-        super(MyLine, self).__init__()
+        super().__init__()
         self.fuzziness = 2
 
     def draw_head(self, context):
diff --git a/gaphas/aspect.py b/gaphas/aspect.py
index d5584fb..91219fa 100644
--- a/gaphas/aspect.py
+++ b/gaphas/aspect.py
@@ -38,7 +38,7 @@ def singledispatch(func):
     return wrapped
 
 
-class ItemFinder(object):
+class ItemFinder:
     """
     Find an item on the canvas.
     """
@@ -54,7 +54,7 @@ class ItemFinder(object):
 Finder = singledispatch(ItemFinder)
 
 
-class ItemSelection(object):
+class ItemSelection:
     """
     A role for items. When dealing with selection.
 
@@ -80,7 +80,7 @@ class ItemSelection(object):
 Selection = singledispatch(ItemSelection)
 
 
-class ItemInMotion(object):
+class ItemInMotion:
     """
     Aspect for dealing with motion on an item.
 
@@ -118,7 +118,7 @@ class ItemInMotion(object):
 InMotion = singledispatch(ItemInMotion)
 
 
-class ItemHandleFinder(object):
+class ItemHandleFinder:
     """
     Deals with the task of finding handles.
     """
@@ -134,7 +134,7 @@ class ItemHandleFinder(object):
 HandleFinder = singledispatch(ItemHandleFinder)
 
 
-class ItemHandleSelection(object):
+class ItemHandleSelection:
     """
     Deal with selection of the handle.
     """
@@ -172,7 +172,7 @@ class ElementHandleSelection(ItemHandleSelection):
         self.view.get_window().set_cursor(cursor)
 
 
-class ItemHandleInMotion(object):
+class ItemHandleInMotion:
     """
     Move a handle (role is applied to the handle)
     """
@@ -251,7 +251,7 @@ class ItemHandleInMotion(object):
 HandleInMotion = singledispatch(ItemHandleInMotion)
 
 
-class ItemConnector(object):
+class ItemConnector:
     """Connect or disconnect an item's handle to another item or port.
 
     """
@@ -329,7 +329,7 @@ class ItemConnector(object):
 Connector = singledispatch(ItemConnector)
 
 
-class ItemConnectionSink(object):
+class ItemConnectionSink:
     """Makes an item a sink.
 
     A sink is another item that an item's handle is connected to like a
@@ -366,7 +366,7 @@ ConnectionSink = singledispatch(ItemConnectionSink)
 #
 
 
-class ItemPaintFocused(object):
+class ItemPaintFocused:
     """
     Paints on top of all items, just for the focused item and only
     when it's hovered (see gaphas.painter.FocusedItemPainter)
diff --git a/gaphas/canvas.py b/gaphas/canvas.py
index d48d291..326f1ae 100644
--- a/gaphas/canvas.py
+++ b/gaphas/canvas.py
@@ -57,7 +57,7 @@ class ConnectionError(Exception):
     """
 
 
-class Context(object):
+class Context:
     """
     Context used for updating and drawing items in a drawing canvas.
 
@@ -86,7 +86,7 @@ def instant_cairo_context():
     return cairo.Context(surface)
 
 
-class Canvas(object):
+class Canvas:
     """
     Container class for items.
     """
@@ -930,7 +930,7 @@ class VariableProjection(solver.Projection):
         return self._var
 
 
-class CanvasProjection(object):
+class CanvasProjection:
     """
     Project a point as Canvas coordinates.  Although this is a
     projection, it behaves like a tuple with two Variables
diff --git a/gaphas/connector.py b/gaphas/connector.py
index b8450c3..1358c34 100644
--- a/gaphas/connector.py
+++ b/gaphas/connector.py
@@ -27,7 +27,7 @@ def deprecated(message, since):
     return _deprecated
 
 
-class Position(object):
+class Position:
     """
     A point constructed of two `Variable`'s.
 
@@ -91,7 +91,7 @@ class Position(object):
         return (self.x, self.y)[index]
 
 
-class Handle(object):
+class Handle:
     """
     Handles are used to support modifications of Items.
 
@@ -178,7 +178,7 @@ class Handle(object):
     __repr__ = __str__
 
 
-class Port(object):
+class Port:
     """Port connectable part of an item.
 
     The Item's handle connects to a port.
@@ -186,7 +186,7 @@ class Port(object):
     """
 
     def __init__(self):
-        super(Port, self).__init__()
+        super().__init__()
 
         self._connectable = True
 
@@ -215,7 +215,7 @@ class LinePort(Port):
     """
 
     def __init__(self, start, end):
-        super(LinePort, self).__init__()
+        super().__init__()
 
         self.start = start
         self.end = end
@@ -250,7 +250,7 @@ class PointPort(Port):
     """
 
     def __init__(self, point):
-        super(PointPort, self).__init__()
+        super().__init__()
         self.point = point
 
     def glue(self, pos):
diff --git a/gaphas/constraint.py b/gaphas/constraint.py
index b78f288..76af493 100644
--- a/gaphas/constraint.py
+++ b/gaphas/constraint.py
@@ -40,7 +40,7 @@ def _update(variable, value):
         variable.value = value
 
 
-class Constraint(object):
+class Constraint:
     """
     Constraint base class.
 
@@ -152,7 +152,7 @@ class EqualsConstraint(Constraint):
     """
 
     def __init__(self, a=None, b=None, delta=0.0):
-        super(EqualsConstraint, self).__init__(a, b, delta)
+        super().__init__(a, b, delta)
         self.a = a
         self.b = b
         self.delta = delta
@@ -194,7 +194,7 @@ class CenterConstraint(Constraint):
     """
 
     def __init__(self, a=None, b=None, center=None):
-        super(CenterConstraint, self).__init__(a, b, center)
+        super().__init__(a, b, center)
         self.a = a
         self.b = b
         self.center = center
@@ -234,7 +234,7 @@ class LessThanConstraint(Constraint):
     """
 
     def __init__(self, smaller=None, bigger=None, delta=0.0):
-        super(LessThanConstraint, self).__init__(smaller, bigger, delta)
+        super().__init__(smaller, bigger, delta)
         self.smaller = smaller
         self.bigger = bigger
         self.delta = delta
@@ -276,7 +276,7 @@ class EquationConstraint(Constraint):
     """
 
     def __init__(self, f, **args):
-        super(EquationConstraint, self).__init__(*list(args.values()))
+        super().__init__(*list(args.values()))
         self._f = f
         self._args = {}
         # see important note on order of operations in __setattr__ below.
@@ -422,7 +422,7 @@ class BalanceConstraint(Constraint):
     """
 
     def __init__(self, band=None, v=None, balance=None):
-        super(BalanceConstraint, self).__init__(band[0], band[1], v)
+        super().__init__(band[0], band[1], v)
         self.band = band
         self.balance = balance
         self.v = v
@@ -455,7 +455,7 @@ class LineConstraint(Constraint):
     """
 
     def __init__(self, line, point):
-        super(LineConstraint, self).__init__(
+        super().__init__(
             line[0][0], line[0][1], line[1][0], line[1][1], point[0], point[1]
         )
 
@@ -535,9 +535,7 @@ class PositionConstraint(Constraint):
     """
 
     def __init__(self, origin, point):
-        super(PositionConstraint, self).__init__(
-            origin[0], origin[1], point[0], point[1]
-        )
+        super().__init__(origin[0], origin[1], point[0], point[1])
 
         self._origin = origin
         self._point = point
@@ -580,7 +578,7 @@ class LineAlignConstraint(Constraint):
     """
 
     def __init__(self, line, point, align=0.5, delta=0.0):
-        super(LineAlignConstraint, self).__init__(
+        super().__init__(
             line[0][0], line[0][1], line[1][0], line[1][1], point[0], point[1]
         )
 
diff --git a/gaphas/decorators.py b/gaphas/decorators.py
index 6015c39..86e0a66 100644
--- a/gaphas/decorators.py
+++ b/gaphas/decorators.py
@@ -11,7 +11,7 @@ from gi.repository import Gtk, GLib
 DEBUG_ASYNC = False
 
 
-class AsyncIO(object):
+class AsyncIO:
     """
     Instead of calling the function, schedule an idle handler at a
     given priority. This requires the async'ed method to be called
@@ -176,7 +176,7 @@ def nonrecursive(func):
     return wrapper
 
 
-class recursive(object):
+class recursive:
     """
     This decorator limits the recursion for a specific function
 
diff --git a/gaphas/examples.py b/gaphas/examples.py
index 63b7aa4..63d157e 100644
--- a/gaphas/examples.py
+++ b/gaphas/examples.py
@@ -15,7 +15,7 @@ class Box(Element):
     """
 
     def __init__(self, width=10, height=10):
-        super(Box, self).__init__(width, height)
+        super().__init__(width, height)
 
     def draw(self, context):
         c = context.cairo
@@ -51,7 +51,7 @@ class PortoBox(Box):
     """
 
     def __init__(self, width=10, height=10):
-        super(PortoBox, self).__init__(width, height)
+        super().__init__(width, height)
 
         # disable default ports
         for p in self._ports:
@@ -86,7 +86,7 @@ class PortoBox(Box):
         self._ports.append(self._lport)
 
     def draw(self, context):
-        super(PortoBox, self).draw(context)
+        super().draw(context)
         c = context.cairo
 
         if context.hovered:
@@ -121,7 +121,7 @@ class Text(Item):
     """
 
     def __init__(self, text=None, plain=False, multiline=False, align_x=1, align_y=-1):
-        super(Text, self).__init__()
+        super().__init__()
         self.text = text is None and "Hello" or text
         self.plain = plain
         self.multiline = multiline
@@ -149,7 +149,7 @@ class FatLine(Item):
     """
 
     def __init__(self):
-        super(FatLine, self).__init__()
+        super().__init__()
         self._handles.extend((Handle(), Handle()))
 
         h1, h2 = self._handles
@@ -180,7 +180,7 @@ class FatLine(Item):
 
 class Circle(Item):
     def __init__(self):
-        super(Circle, self).__init__()
+        super().__init__()
         self._handles.extend((Handle(), Handle()))
 
     def _set_radius(self, r):
@@ -196,7 +196,7 @@ class Circle(Item):
     radius = property(_get_radius, _set_radius)
 
     def setup_canvas(self):
-        super(Circle, self).setup_canvas()
+        super().setup_canvas()
         h1, h2 = self._handles
         h1.movable = False
 
diff --git a/gaphas/freehand.py b/gaphas/freehand.py
index 0d1cbcf..90292a7 100644
--- a/gaphas/freehand.py
+++ b/gaphas/freehand.py
@@ -15,7 +15,7 @@ from random import Random
 from gaphas.painter import Context
 
 
-class FreeHandCairoContext(object):
+class FreeHandCairoContext:
 
     KAPPA = 0.5522847498
 
@@ -156,7 +156,7 @@ class FreeHandCairoContext(object):
             self.close_path()
 
 
-class FreeHandPainter(object):
+class FreeHandPainter:
     def __init__(self, subpainter, sloppiness=1.0, view=None):
         self.subpainter = subpainter
         self.view = view
diff --git a/gaphas/geometry.py b/gaphas/geometry.py
index c7e4b22..b3e7a38 100644
--- a/gaphas/geometry.py
+++ b/gaphas/geometry.py
@@ -10,7 +10,7 @@ A point is represented as a tuple `(x, y)`.
 from math import sqrt
 
 
-class Rectangle(object):
+class Rectangle:
     """
     Python Rectangle implementation. Rectangles can be added (union),
     substituted (intersection) and points and rectangles can be tested
diff --git a/gaphas/guide.py b/gaphas/guide.py
index b897e4e..bab3220 100644
--- a/gaphas/guide.py
+++ b/gaphas/guide.py
@@ -9,7 +9,7 @@ from gaphas.aspect import ItemInMotion, ItemHandleInMotion, ItemPaintFocused
 from gaphas.item import Item, Element, Line
 
 
-class ItemGuide(object):
+class ItemGuide:
     """
     Get edges on an item, on which we can align the items.
     """
@@ -79,7 +79,7 @@ class LineGuide(ItemGuide):
                         yield h.pos.x
 
 
-class Guides(object):
+class Guides:
     def __init__(self, v, h):
         self.v = v
         self.h = h
@@ -91,7 +91,7 @@ class Guides(object):
         return self.h
 
 
-class GuideMixin(object):
+class GuideMixin:
     """
     Helper methods for guides.
     """
@@ -229,7 +229,7 @@ class GuidedItemInMotion(GuideMixin, ItemInMotion):
         newpos = px + dx, py + dy
 
         # Call super class, with new position
-        sink = super(GuidedItemInMotion, self).move(newpos)
+        sink = super().move(newpos)
 
         self.queue_draw_guides()
 
@@ -258,7 +258,7 @@ class GuidedItemHandleInMotion(GuideMixin, ItemHandleInMotion):
 
     def move(self, pos):
 
-        sink = super(GuidedItemHandleInMotion, self).move(pos)
+        sink = super().move(pos)
 
         if not sink:
             item = self.item
diff --git a/gaphas/item.py b/gaphas/item.py
index 00cde94..83cfe02 100644
--- a/gaphas/item.py
+++ b/gaphas/item.py
@@ -25,7 +25,7 @@ from gaphas.state import (
 )
 
 
-class Item(object):
+class Item:
     """
     Base class (or interface) for items on a canvas.Canvas.
 
@@ -314,7 +314,7 @@ class Element(Item):
     min_height = solvable(strength=REQUIRED, varname="_min_height")
 
     def __init__(self, width=10, height=10):
-        super(Element, self).__init__()
+        super().__init__()
         self._handles = [h(strength=VERY_STRONG) for h in [Handle] * 4]
 
         handles = self._handles
@@ -351,7 +351,7 @@ class Element(Item):
         # self.constraints.append(EqualsConstraint(p1[1], p2[1], delta))
 
     def setup_canvas(self):
-        super(Element, self).setup_canvas()
+        super().setup_canvas()
 
         # Trigger solver to honour width/height by SE handle pos
         self._handles[SE].pos.x.dirty()
@@ -464,7 +464,7 @@ class Line(Item):
     """
 
     def __init__(self):
-        super(Line, self).__init__()
+        super().__init__()
         self._handles = [Handle(connectable=True), Handle((10, 10), connectable=True)]
         self._ports = []
         self._update_ports()
@@ -578,14 +578,14 @@ class Line(Item):
         """
         Setup constraints. In this case orthogonal.
         """
-        super(Line, self).setup_canvas()
+        super().setup_canvas()
         self._update_orthogonal_constraints(self.orthogonal)
 
     def teardown_canvas(self):
         """
         Remove constraints created in setup_canvas().
         """
-        super(Line, self).teardown_canvas()
+        super().teardown_canvas()
         for c in self._orthogonal_constraints:
             self.canvas.solver.remove_constraint(c)
 
@@ -649,7 +649,7 @@ class Line(Item):
     def post_update(self, context):
         """
         """
-        super(Line, self).post_update(context)
+        super().post_update(context)
         h0, h1 = self._handles[:2]
         p0, p1 = h0.pos, h1.pos
         self._head_angle = atan2(p1.y - p0.y, p1.x - p0.x)
diff --git a/gaphas/matrix.py b/gaphas/matrix.py
index 64be8fd..8ec280e 100644
--- a/gaphas/matrix.py
+++ b/gaphas/matrix.py
@@ -14,7 +14,7 @@ import cairo
 from gaphas.state import observed, reversible_method
 
 
-class Matrix(object):
+class Matrix:
     """
     Matrix wrapper. This version sends @observed messages on state changes
 
diff --git a/gaphas/painter.py b/gaphas/painter.py
index c0dfd02..313bd8c 100644
--- a/gaphas/painter.py
+++ b/gaphas/painter.py
@@ -21,7 +21,7 @@ DEBUG_DRAW_BOUNDING_BOX = False
 TOLERANCE = 0.8
 
 
-class Painter(object):
+class Painter:
     """
     Painter interface.
     """
@@ -46,7 +46,7 @@ class PainterChain(Painter):
     """
 
     def __init__(self, view=None):
-        super(PainterChain, self).__init__(view)
+        super().__init__(view)
         self._painters = []
 
     def set_view(self, view):
@@ -84,7 +84,7 @@ class DrawContext(Context):
     """
 
     def __init__(self, **kwargs):
-        super(DrawContext, self).__init__(**kwargs)
+        super().__init__(**kwargs)
 
 
 class ItemPainter(Painter):
@@ -146,7 +146,7 @@ class ItemPainter(Painter):
         self._draw_items(context.items, cairo, context.area)
 
 
-class CairoBoundingBoxContext(object):
+class CairoBoundingBoxContext:
     """
     Delegate all calls to the wrapped CairoBoundingBoxContext,
     intercept ``stroke()``, ``fill()`` and a few others so the
@@ -252,7 +252,7 @@ class BoundingBoxPainter(ItemPainter):
 
     def _draw_item(self, item, cairo, area=None):
         cairo = CairoBoundingBoxContext(cairo)
-        super(BoundingBoxPainter, self)._draw_item(item, cairo)
+        super()._draw_item(item, cairo)
         bounds = cairo.get_bounds()
 
         # Update bounding box with handles.
diff --git a/gaphas/segment.py b/gaphas/segment.py
index cfc9520..438e985 100644
--- a/gaphas/segment.py
+++ b/gaphas/segment.py
@@ -12,13 +12,13 @@ from gaphas.item import Line
 
 
 @singledispatch
-class Segment(object):
+class Segment:
     def __init__(self, item, view):
         raise TypeError
 
 
 @Segment.register(Line)
-class LineSegment(object):
+class LineSegment:
     def __init__(self, item, view):
         self.item = item
         self.view = view
@@ -184,7 +184,7 @@ class SegmentHandleFinder(ItemHandleFinder):
                 handle = segment.split(pos)
 
         if not handle:
-            item, handle = super(SegmentHandleFinder, self).get_handle_at_point(pos)
+            item, handle = super().get_handle_at_point(pos)
         return item, handle
 
 
diff --git a/gaphas/solver.py b/gaphas/solver.py
index afb6744..d42d89e 100644
--- a/gaphas/solver.py
+++ b/gaphas/solver.py
@@ -48,7 +48,7 @@ VERY_STRONG = 40
 REQUIRED = 100
 
 
-class Variable(object):
+class Variable:
     """Representation of a variable in the constraint solver.
 
     Each Variable has a @value and a @strength. In a constraint the weakest
@@ -309,7 +309,7 @@ class Variable(object):
         return self._value.__rtruediv__(other)
 
 
-class Projection(object):
+class Projection:
     """
     Projections are used to convert values from one space to another,
     e.g. from Canvas to Item space or visa versa.
@@ -366,7 +366,7 @@ class Projection(object):
     __repr__ = __str__
 
 
-class Solver(object):
+class Solver:
     """
     Solve constraints. A constraint should have accompanying
     variables.
@@ -622,7 +622,7 @@ class Solver(object):
             self._solving = False
 
 
-class solvable(object):
+class solvable:
     """
     Easy-to-use drop Variable descriptor.
 
diff --git a/gaphas/table.py b/gaphas/table.py
index 913630e..e0722c9 100644
--- a/gaphas/table.py
+++ b/gaphas/table.py
@@ -5,7 +5,7 @@ one would in a database table, with indexes on the desired "columns."
 from functools import reduce
 
 
-class Table(object):
+class Table:
     """
     A Table structure with indexing. Optimized for lookups.
     """
@@ -61,7 +61,7 @@ class Table(object):
             if v in index[n]:
                 index[n][v].add(data)
             else:
-                index[n][v] = set([data])
+                index[n][v] = {data}
 
     def delete(self, *_row, **kv):
         """
diff --git a/gaphas/tool.py b/gaphas/tool.py
index 5c95c92..ab768aa 100644
--- a/gaphas/tool.py
+++ b/gaphas/tool.py
@@ -48,7 +48,7 @@ DEBUG_TOOL_CHAIN = False
 Event = Context
 
 
-class Tool(object):
+class Tool:
     """
     Base class for a tool. This class
     A word on click events:
@@ -142,7 +142,7 @@ class ToolChain(Tool):
     """
 
     def __init__(self, view=None):
-        super(ToolChain, self).__init__(view)
+        super().__init__(view)
         self._tools = []
         self._grabbed_tool = None
 
@@ -241,7 +241,7 @@ class ItemTool(Tool):
     """
 
     def __init__(self, view=None, buttons=(1,)):
-        super(ItemTool, self).__init__(view)
+        super().__init__(view)
         self._buttons = buttons
         self._movable_items = set()
 
@@ -327,7 +327,7 @@ class HandleTool(Tool):
     """
 
     def __init__(self, view=None):
-        super(HandleTool, self).__init__(view)
+        super().__init__(view)
         self.grabbed_handle = None
         self.grabbed_item = None
         self.motion_handle = None
@@ -431,7 +431,7 @@ class HandleTool(Tool):
 
 class RubberbandTool(Tool):
     def __init__(self, view=None):
-        super(RubberbandTool, self).__init__(view)
+        super().__init__(view)
         self.x0, self.y0, self.x1, self.y1 = 0, 0, 0, 0
 
     def on_button_press(self, event):
@@ -487,7 +487,7 @@ class PanTool(Tool):
     """
 
     def __init__(self, view=None):
-        super(PanTool, self).__init__(view)
+        super().__init__(view)
         self.x0, self.y0 = 0, 0
         self.speed = 10
 
@@ -551,7 +551,7 @@ class ZoomTool(Tool):
     """
 
     def __init__(self, view=None):
-        super(ZoomTool, self).__init__(view)
+        super().__init__(view)
         self.x0, self.y0 = 0, 0
         self.lastdiff = 0
 
@@ -622,7 +622,7 @@ class ZoomTool(Tool):
 
 class PlacementTool(Tool):
     def __init__(self, view, factory, handle_tool, handle_index):
-        super(PlacementTool, self).__init__(view)
+        super().__init__(view)
         self._factory = factory
         self.handle_tool = handle_tool
         handle_tool.set_view(view)
@@ -683,7 +683,7 @@ class TextEditTool(Tool):
     """
 
     def __init__(self, view=None):
-        super(TextEditTool, self).__init__(view)
+        super().__init__(view)
 
     def on_double_click(self, event):
         """
@@ -782,7 +782,7 @@ class ConnectHandleTool(HandleTool):
                 pos = event.get_coords()[1:]
                 self.connect(item, handle, pos)
         finally:
-            return super(ConnectHandleTool, self).on_button_release(event)
+            return super().on_button_release(event)
 
 
 def DefaultTool(view=None):
diff --git a/gaphas/tree.py b/gaphas/tree.py
index 6dbf1c0..a1c3310 100644
--- a/gaphas/tree.py
+++ b/gaphas/tree.py
@@ -5,7 +5,7 @@ Simple class containing the tree structure for the canvas items.
 from operator import attrgetter
 
 
-class Tree(object):
+class Tree:
     """
     A Tree structure. Nodes are stores in a depth-first order.
 
@@ -127,8 +127,7 @@ class Tree(object):
         children = self.get_children(node)
         for c in children:
             yield c
-            for cc in self.get_all_children(c):
-                yield cc
+            yield from self.get_all_children(c)
 
     def get_ancestors(self, node):
         """
diff --git a/gaphas/view.py b/gaphas/view.py
index f6235ad..0ceb412 100644
--- a/gaphas/view.py
+++ b/gaphas/view.py
@@ -20,7 +20,7 @@ DEBUG_DRAW_QUADTREE = False
 DEFAULT_CURSOR = Gdk.CursorType.LEFT_PTR
 
 
-class View(object):
+class View:
     """
     View class for gaphas.Canvas objects.
     """
@@ -583,7 +583,7 @@ class GtkView(Gtk.DrawingArea, Gtk.Scrollable, View):
             self._clear_matrices()
             self._canvas.unregister_view(self)
 
-        super(GtkView, self)._set_canvas(canvas)
+        super()._set_canvas(canvas)
 
         if self._canvas:
             self._canvas.register_view(self)
@@ -610,7 +610,7 @@ class GtkView(Gtk.DrawingArea, Gtk.Scrollable, View):
         """
         Zoom in/out by factor ``factor``.
         """
-        super(GtkView, self).zoom(factor)
+        super().zoom(factor)
         self.queue_draw_refresh()
 
     @AsyncIO(single=True)
@@ -768,7 +768,7 @@ class GtkView(Gtk.DrawingArea, Gtk.Scrollable, View):
         cr.rectangle(0, 0, 0, 0)
         cr.clip()
         try:
-            super(GtkView, self).update_bounding_box(cr, items)
+            super().update_bounding_box(cr, items)
         finally:
             cr.restore()
 
diff --git a/tests/conftest.py b/tests/conftest.py
index fa007ad..3c9d2c3 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -12,7 +12,7 @@ from gaphas.tool import ConnectHandleTool
 from gaphas.view import GtkView
 
 
-class SimpleCanvas(object):
+class SimpleCanvas:
     """Creates a test canvas object.
 
     Adds a view, canvas, and handle connection tool to a test
diff --git a/tests/test_aspect.py b/tests/test_aspect.py
index 1d68e72..b1c004b 100644
--- a/tests/test_aspect.py
+++ b/tests/test_aspect.py
@@ -9,7 +9,7 @@ from gaphas.canvas import Canvas
 from gaphas.view import View
 
 
-class CanvasViewItem(object):
+class CanvasViewItem:
     def __init__(self):
         self.canvas = Canvas()
         self.view = View(self.canvas)
diff --git a/tests/test_element.py b/tests/test_element.py
index f9ab7b6..06b297d 100644
--- a/tests/test_element.py
+++ b/tests/test_element.py
@@ -6,7 +6,7 @@ from gaphas.examples import Box
 from gaphas.item import NW, NE, SE, SW
 
 
-class CanvasBox(object):
+class CanvasBox:
     def __init__(self):
         self.canvas = Canvas()
         self.box = Box()
diff --git a/tests/test_guide.py b/tests/test_guide.py
index 0e053c8..7825072 100644
--- a/tests/test_guide.py
+++ b/tests/test_guide.py
@@ -7,7 +7,7 @@ from gaphas.item import Element, Line
 from gaphas.view import GtkView
 
 
-class Window(object):
+class Window:
     def __init__(self):
         self.canvas = Canvas()
         self.view = GtkView(self.canvas)
diff --git a/tests/test_item.py b/tests/test_item.py
index e492429..a3f56b6 100644
--- a/tests/test_item.py
+++ b/tests/test_item.py
@@ -11,7 +11,7 @@ from gaphas.item import Item
 from gaphas.solver import Variable
 
 
-class ItemPosition(object):
+class ItemPosition:
     def __init__(self):
         self.item = Item()
         self.pos1 = Variable(1), Variable(2)
diff --git a/tests/test_pickle.py b/tests/test_pickle.py
index 9c8778d..b44dcc7 100644
--- a/tests/test_pickle.py
+++ b/tests/test_pickle.py
@@ -24,7 +24,7 @@ class MyPickler(pickle.Pickler):
             raise e
 
 
-class MyDisconnect(object):
+class MyDisconnect:
     """Create a disconnect object.
 
     The disconnect object should be located at top-level, so the pickle code
@@ -36,7 +36,7 @@ class MyDisconnect(object):
         pass
 
 
-class CanvasFixture(object):
+class CanvasFixture:
     def __init__(self):
         self.canvas = Canvas()
         self.box = Box()
diff --git a/tests/test_segment.py b/tests/test_segment.py
index 33c7fa7..a44ca04 100644
--- a/tests/test_segment.py
+++ b/tests/test_segment.py
@@ -9,7 +9,7 @@ from gaphas.segment import *
 from gaphas.view import View
 
 
-class SegmentFixture(object):
+class SegmentFixture:
     def __init__(self):
         self.canvas = Canvas()
         self.line = Line()
diff --git a/tests/test_solver.py b/tests/test_solver.py
index c7949aa..93ab750 100644
--- a/tests/test_solver.py
+++ b/tests/test_solver.py
@@ -22,7 +22,7 @@ REPEAT = 30
 NUMBER = 1000
 
 
-class SolverFixture(object):
+class SolverFixture:
     def __init__(self):
         self.solver = Solver()
         self.a = Variable(1, 30)
diff --git a/tests/test_state.py b/tests/test_state.py
index c97fe2b..f1fbf55 100644
--- a/tests/test_state.py
+++ b/tests/test_state.py
@@ -3,7 +3,7 @@ import sys
 from gaphas.state import reversible_pair, observed, _reverse
 
 
-class SList(object):
+class SList:
     def __init__(self):
         self.list = list()
 
diff --git a/tests/test_tool.py b/tests/test_tool.py
index 9a4865a..6bd114a 100644
--- a/tests/test_tool.py
+++ b/tests/test_tool.py
@@ -56,7 +56,7 @@ def test_glue_no_port_no_can_glue(simple_canvas):
 
     class Tool(ConnectHandleTool):
         def __init__(self, *args):
-            super(Tool, self).__init__(*args)
+            super().__init__(*args)
             self._calls = 0
 
         def can_glue(self, *args):
diff --git a/tests/test_view.py b/tests/test_view.py
index 85b30d7..b2a3f9a 100644
--- a/tests/test_view.py
+++ b/tests/test_view.py
@@ -12,7 +12,7 @@ from gaphas.item import Line
 from gaphas.view import View, GtkView
 
 
-class ViewFixture(object):
+class ViewFixture:
     def __init__(self):
         self.canvas = Canvas()
         self.view = GtkView(self.canvas)