diff --git a/veerer/__init__.py b/veerer/__init__.py
index 8011dc7..8a79612 100644
--- a/veerer/__init__.py
+++ b/veerer/__init__.py
@@ -4,7 +4,6 @@
 A Python module to deal with Veering triangulation and L^infinity
 Delaunay decomposition of surfaces.
 """
-from __future__ import absolute_import
 
 from .constants import RED, BLUE, PURPLE, GREEN, HORIZONTAL, VERTICAL, RIGHT, LEFT, UP, DOWN
 from .triangulation import Triangulation
@@ -19,4 +18,4 @@
     from .layout import FlatVeeringTriangulationLayout
     from .measured_train_track import MeasuredTrainTrack
 
-del sage, absolute_import
+del sage
diff --git a/veerer/automaton.py b/veerer/automaton.py
index c39dd2f..e6722ee 100644
--- a/veerer/automaton.py
+++ b/veerer/automaton.py
@@ -1,8 +1,6 @@
 r"""
 Train-track and triangulations automata.
 """
-from __future__ import print_function, absolute_import
-from six.moves import range, map, filter, zip
 
 import os
 import sys
diff --git a/veerer/cover.py b/veerer/cover.py
index c97a97a..bfa48d3 100644
--- a/veerer/cover.py
+++ b/veerer/cover.py
@@ -2,9 +2,6 @@
 Covering of triangulations
 """
 
-from __future__ import absolute_import, print_function
-from six.moves import range, map, zip
-
 from array import array
 
 from .permutation import *
diff --git a/veerer/flip_sequence.py b/veerer/flip_sequence.py
index 8217576..e960058 100644
--- a/veerer/flip_sequence.py
+++ b/veerer/flip_sequence.py
@@ -55,8 +55,6 @@
 # along with veerer. If not, see <https://www.gnu.org/licenses/>.
 ######################################################################
 
-from __future__ import absolute_import
-
 from .constants import colour_from_char, colour_to_char, RED, BLUE, PURPLE, GREEN, HORIZONTAL, VERTICAL
 from .permutation import perm_init, perm_check, perm_id, perm_is_one, perm_preimage, perm_invert, perm_cycle_string, perm_compose, perm_pow, perm_conjugate
 from .veering_triangulation import VeeringTriangulation
diff --git a/veerer/misc.py b/veerer/misc.py
index 60f6ec0..6351938 100644
--- a/veerer/misc.py
+++ b/veerer/misc.py
@@ -2,9 +2,6 @@
 Utility functions.
 """
 
-from __future__ import print_function, absolute_import
-from six.moves import range, map, filter, zip
-
 from .env import ppl
 
 def det2(u, v):
diff --git a/veerer/permutation.py b/veerer/permutation.py
index 83d51e0..27d1015 100644
--- a/veerer/permutation.py
+++ b/veerer/permutation.py
@@ -10,8 +10,6 @@
   such array should not be allocated each time the function
   is called.
 """
-from __future__ import absolute_import, print_function
-from six.moves import range, map, filter, zip
 
 from array import array
 from math import log
diff --git a/veerer/triangulation.py b/veerer/triangulation.py
index cbf41ba..032a028 100644
--- a/veerer/triangulation.py
+++ b/veerer/triangulation.py
@@ -1,8 +1,6 @@
 r"""
 Triangulation of surfaces.
 """
-from __future__ import absolute_import, print_function
-from six.moves import range, map, filter, zip
 
 from array import array
 from .permutation import *
diff --git a/veerer/veering_triangulation.py b/veerer/veering_triangulation.py
index 62a6d07..70451dc 100644
--- a/veerer/veering_triangulation.py
+++ b/veerer/veering_triangulation.py
@@ -5,8 +5,6 @@
 to folded edges). It is said to be in canonical form if it starts with cycle
 representatives.
 """
-from __future__ import print_function, absolute_import
-from six.moves import range, map, filter, zip
 
 import numbers