diff --git a/Source/atom.py b/Source/atom.py
index c964930..dc9470b 100644
--- a/Source/atom.py
+++ b/Source/atom.py
@@ -1,3 +1,7 @@
+
+from __future__ import division
+from __future__ import print_function
+
 import string, Source.lib, Source.group
 
 
diff --git a/Source/bonds.py b/Source/bonds.py
index d9da657..6859ef3 100644
--- a/Source/bonds.py
+++ b/Source/bonds.py
@@ -1,4 +1,7 @@
+
 from __future__ import division
+from __future__ import print_function
+
 import pickle,sys,os,math,Source.calculations
 
 
diff --git a/Source/calculations.py b/Source/calculations.py
index ae71054..07dd574 100644
--- a/Source/calculations.py
+++ b/Source/calculations.py
@@ -1,5 +1,7 @@
 
 from __future__ import division
+from __future__ import print_function
+
 import math, Source.protonate, Source.bonds,copy, sys
 
 
diff --git a/Source/conformation_container.py b/Source/conformation_container.py
index f042192..1cf9c21 100644
--- a/Source/conformation_container.py
+++ b/Source/conformation_container.py
@@ -3,6 +3,8 @@
 #
 
 from __future__ import division
+from __future__ import print_function
+
 import Source.group, Source.determinants, Source.determinant, Source.ligand, Source.output, Source.coupled_groups, functools
 
 class Conformation_container:
diff --git a/Source/coupled_groups.py b/Source/coupled_groups.py
index 5be0513..2ee80e6 100644
--- a/Source/coupled_groups.py
+++ b/Source/coupled_groups.py
@@ -1,5 +1,7 @@
 
 from __future__ import division
+from __future__ import print_function
+
 import math, Source.output, Source.group, Source.lib, itertools
 
 
diff --git a/Source/determinant.py b/Source/determinant.py
index 3be7a02..5085ca1 100644
--- a/Source/determinant.py
+++ b/Source/determinant.py
@@ -1,4 +1,7 @@
 
+from __future__ import division
+from __future__ import print_function
+
 class Determinant:
     """
         Determinant class - set up for later structurization
diff --git a/Source/determinants.py b/Source/determinants.py
index 8f2dc60..df8b66e 100644
--- a/Source/determinants.py
+++ b/Source/determinants.py
@@ -1,3 +1,7 @@
+
+from __future__ import division
+from __future__ import print_function
+
 import math, time
 
 import Source.iterative, Source.lib, Source.vector_algebra
diff --git a/Source/group.py b/Source/group.py
index 99fabaf..56a237d 100644
--- a/Source/group.py
+++ b/Source/group.py
@@ -3,6 +3,8 @@
 #
 
 from __future__ import division
+from __future__ import print_function
+
 import Source.ligand, Source.determinant, Source.ligand_pka_values, math, Source.protonate
 
 my_protonator = Source.protonate.Protonate(verbose=False)
diff --git a/Source/iterative.py b/Source/iterative.py
index c994867..884d39b 100644
--- a/Source/iterative.py
+++ b/Source/iterative.py
@@ -1,3 +1,7 @@
+
+from __future__ import division
+from __future__ import print_function
+
 import math, time
 import Source.lib as lib
 from Source.determinant import Determinant
diff --git a/Source/lib.py b/Source/lib.py
index 43b471d..6e11a07 100755
--- a/Source/lib.py
+++ b/Source/lib.py
@@ -1,5 +1,8 @@
 #!/usr/bin/python
 
+from __future__ import division
+from __future__ import print_function
+
 import string, sys, copy, math, os
 
 
diff --git a/Source/ligand.py b/Source/ligand.py
index d745d51..3060b61 100755
--- a/Source/ligand.py
+++ b/Source/ligand.py
@@ -1,5 +1,8 @@
 #!/usr/bin/python
 
+from __future__ import division
+from __future__ import print_function
+
 import sys, Source.calculations
 from Source.vector_algebra import *
 
diff --git a/Source/ligand_pka_values.py b/Source/ligand_pka_values.py
index 591a77c..98a3a14 100644
--- a/Source/ligand_pka_values.py
+++ b/Source/ligand_pka_values.py
@@ -1,5 +1,8 @@
 #!/usr/bin/env python
 
+from __future__ import division
+from __future__ import print_function
+
 import Source.molecular_container, Source.calculations, Source.calculations, Source.parameters, Source.pdb, Source.lib, os, subprocess, sys
 
 class ligand_pka_values:
diff --git a/Source/molecular_container.py b/Source/molecular_container.py
index e95be4c..e6df03e 100755
--- a/Source/molecular_container.py
+++ b/Source/molecular_container.py
@@ -4,6 +4,7 @@
 #
 #
 from __future__ import division
+from __future__ import print_function
 import os, Source.pdb, sys, Source.version, Source.output, Source.conformation_container, Source.group, Source.lib
 
 class Molecular_container:
diff --git a/Source/output.py b/Source/output.py
index 16a97e1..b944442 100644
--- a/Source/output.py
+++ b/Source/output.py
@@ -1,3 +1,7 @@
+
+from __future__ import division
+from __future__ import print_function
+
 import sys
 import Source.lib
 
diff --git a/Source/parameters.py b/Source/parameters.py
index 80d50f1..2dfafff 100644
--- a/Source/parameters.py
+++ b/Source/parameters.py
@@ -1,3 +1,7 @@
+
+from __future__ import division
+from __future__ import print_function
+
 import math
 import Source.lib as lib
 import sys, os
diff --git a/Source/pdb.py b/Source/pdb.py
index d0a3bfa..01b37a3 100644
--- a/Source/pdb.py
+++ b/Source/pdb.py
@@ -1,3 +1,7 @@
+
+from __future__ import division
+from __future__ import print_function
+
 import string, sys, copy, Source.lib
 from Source.atom import Atom
 from Source.conformation_container import Conformation_container
diff --git a/Source/protonate.py b/Source/protonate.py
index fcc46e4..7d26344 100755
--- a/Source/protonate.py
+++ b/Source/protonate.py
@@ -1,6 +1,7 @@
 #!/usr/bin/python
 
 from __future__ import division
+from __future__ import print_function
 from Source.vector_algebra import *
 import Source.bonds, Source.pdb, Source.atom
 
diff --git a/Source/vector_algebra.py b/Source/vector_algebra.py
index 0603ce9..0b9f0bb 100644
--- a/Source/vector_algebra.py
+++ b/Source/vector_algebra.py
@@ -1,3 +1,5 @@
+from __future__ import division
+from __future__ import print_function
 import math
 
 class vector:
diff --git a/Source/version.py b/Source/version.py
index 5a5f603..07ec22c 100644
--- a/Source/version.py
+++ b/Source/version.py
@@ -1,3 +1,5 @@
+from __future__ import division
+from __future__ import print_function
 import math
 import Source.lib as lib
 import sys, os
diff --git a/Tests/runtest.py b/Tests/runtest.py
index 7bcef10..8f7710e 100755
--- a/Tests/runtest.py
+++ b/Tests/runtest.py
@@ -2,6 +2,9 @@
 
 """ Run test for test pdbs """
 
+from __future__ import division
+from __future__ import print_function
+
 from subprocess import call
 import os, re
 import sys