diff --git a/src/__init__.py b/src/__init__.py
index e69de29..6a00efb 100644
--- a/src/__init__.py
+++ b/src/__init__.py
@@ -0,0 +1,4 @@
+# For relative imports to work in Python 3.6
+import os, sys
+sys.path = [ os.path.dirname(os.path.realpath(__file__)) ] + sys.path
+
diff --git a/src/checkpoint.py b/src/checkpoint.py
index 71dc6b9..fa9addd 100644
--- a/src/checkpoint.py
+++ b/src/checkpoint.py
@@ -25,10 +25,10 @@
 #   scemama@irsamc.ups-tlse.fr
 
 
-from .irpf90_t import *
-from .util import *
-from .variables import variables
-from .modules import modules
+from irpf90_t import *
+from util import *
+from variables import variables
+from modules import modules
 
 CHECKPOINT_UNIT_NUMBER=63
 
diff --git a/src/codelet.py b/src/codelet.py
index 6216d45..b159ed3 100644
--- a/src/codelet.py
+++ b/src/codelet.py
@@ -24,8 +24,8 @@
 #   31062 Toulouse Cedex 4      
 #   scemama@irsamc.ups-tlse.fr
 
-from .command_line import command_line
-from . import irpf90_t
+from command_line import command_line
+import irpf90_t
 
 def run():
   template = """
diff --git a/src/command_line.py b/src/command_line.py
index db8ccbc..4d21e87 100644
--- a/src/command_line.py
+++ b/src/command_line.py
@@ -26,7 +26,7 @@
 
 
 import getopt, sys
-from .version import version
+from version import version
 import re
 
 description = "IRPF90 Fortran preprocessor."
@@ -248,9 +248,9 @@ def do_$LONG(self):
     return self._do_$LONG
 do_$LONG = property(fget=do_$LONG)
 """
-  for short in options:
-    long = options[short][0]
-    exec(t.replace("$LONG",int).replace("$SHORT",short)) #in locals()
+  for short_opt in options:
+    long_opt = options[short_opt][0]
+    exec(t.replace("$LONG",long_opt).replace("$SHORT",short_opt)) #in locals()
 
   def do_run(self):
    if '_do_run' not in self.__dict__:
diff --git a/src/create_man.py b/src/create_man.py
index 5d2102c..5081e8d 100644
--- a/src/create_man.py
+++ b/src/create_man.py
@@ -25,12 +25,12 @@
 #   scemama@irsamc.ups-tlse.fr
 
 
-from .variable  import Variable
-from .variables import variables
-from .subroutine  import Sub
-from .subroutines import subroutines
-from .irpf90_t  import *
-from .util import *
+from variable  import Variable
+from variables import variables
+from subroutine  import Sub
+from subroutines import subroutines
+from irpf90_t  import *
+from util import *
 
 
 def do_print_short(file,var):
@@ -295,7 +295,7 @@ def do_print_subroutines_rst(sub):
 
 ######################################################################
 def run():
-  from . import parsed_text
+  import parsed_text
   import os,sys
   pid1 = os.fork()
   if pid1 == 0:
diff --git a/src/error.py b/src/error.py
index 907b34b..77d8f82 100644
--- a/src/error.py
+++ b/src/error.py
@@ -26,8 +26,8 @@
 
 
 import sys
-from .irpf90_t import *
-from .command_line import command_line
+from irpf90_t import *
+from command_line import command_line
 do_warnings = command_line.do_warnings
 
 ######################################################################
diff --git a/src/init.py b/src/init.py
index df50e02..10b32f0 100644
--- a/src/init.py
+++ b/src/init.py
@@ -27,10 +27,10 @@
 
 import os
 
-from . import util
-from . import makefile
-from . import irpf90_t
-from .command_line import command_line
+import util
+import makefile
+import irpf90_t
+from command_line import command_line
 
 initialized = False
 
diff --git a/src/irp_stack.py b/src/irp_stack.py
index 00bb755..27b1845 100644
--- a/src/irp_stack.py
+++ b/src/irp_stack.py
@@ -25,14 +25,14 @@
 #   scemama@irsamc.ups-tlse.fr
 
 
-from . import util 
-from .command_line import command_line
+import util 
+from command_line import command_line
 
 do_debug = command_line.do_debug
 do_openmp = command_line.do_openmp
 do_memory = command_line.do_memory
 
-from . import irpf90_t
+import irpf90_t
 
 FILENAME = irpf90_t.irpdir+"irp_stack.irp.F90"
 
diff --git a/src/irpf90.py b/src/irpf90.py
index eefe779..6e483ac 100644
--- a/src/irpf90.py
+++ b/src/irpf90.py
@@ -26,16 +26,15 @@
 
 
 
-from . import vim
+import vim
 import os,sys
 try:
   wd = os.path.abspath(os.path.dirname(__file__))
   sys.path.insert(0,(wd+"/../src/"))
 except:
   pass
-sys.setcheckinterval(1000)
 
-from .command_line import command_line
+from command_line import command_line
 
 def main():
 
@@ -45,16 +44,16 @@ def main():
     command_line.usage()
 
   if command_line.do_version:
-    from .version import version
+    from version import version
     print(version)
 
-  from .init import init
+  from init import init
   if command_line.do_init:
     init()
 
   if command_line.do_preprocess:
     init()
-    from .preprocessed_text import preprocessed_text
+    from preprocessed_text import preprocessed_text
     for filename,text in preprocessed_text:
       if filename in command_line.preprocessed:
         for line in text:
@@ -62,7 +61,7 @@ def main():
 
 
   if command_line.do_touch:
-    from .variables import variables
+    from variables import variables
     for var in command_line.touched:
       if var not in variables:
         print("%s is not an IRP entity"%(var,))
@@ -79,39 +78,39 @@ def main():
 
   init()
 
-  from . import irp_stack
+  import irp_stack
   irp_stack.create()
 
-  from . import makefile
+  import makefile
   makefile.create()
 
   if command_line.do_codelet:
-     from . import profile
+     import profile
      profile.build_rdtsc()
-     from . import codelet
+     import codelet
      codelet.run()
 
-  from .modules import modules, write_module
+  from modules import modules, write_module
   for m in list(modules.keys()):
     write_module(modules[m])
 
   makefile.run()
 
-  from . import touches
+  import touches
   touches.create()
 
 #  import checkpoint
 #  checkpoint.create()
 
-  from . import create_man
+  import create_man
   create_man.run()
 
   if command_line.do_profile:
-    from . import profile
+    import profile
     profile.run()
 
   if command_line.do_openmp:
-    from . import locks
+    import locks
     locks.create()
 
 if __name__ == '__main__':
diff --git a/src/irpf90_t.py b/src/irpf90_t.py
index c372d72..2c63fef 100644
--- a/src/irpf90_t.py
+++ b/src/irpf90_t.py
@@ -29,7 +29,7 @@ from zlib import crc32
 
 irpdir = "IRPF90_temp/"
 mandir = "IRPF90_man/"
-irp_id = abs(crc32(os.getcwd()))
+irp_id = abs(crc32(os.getcwd().encode()))
 
 
 class Line(object):
@@ -387,7 +387,7 @@ class Provide_all (Line):
 
 def create_irpf90_files():
   result = []
-  from .command_line import command_line
+  from command_line import command_line
   import os
   def is_irpf90_file(filename):
     return filename.endswith(".irp.f") and not filename.startswith('.')
diff --git a/src/irpman.py b/src/irpman.py
index 06cbfd9..39a0e20 100755
--- a/src/irpman.py
+++ b/src/irpman.py
@@ -29,7 +29,7 @@ import os
 import sys
 
 wd = os.path.abspath(os.path.dirname(__file__))
-from .irpf90_t import mandir
+from irpf90_t import mandir
 filename = sys.argv[1].lower()+".l"
 if filename not in os.listdir(mandir):
    print("%s does not exist"%(sys.argv[1]))
diff --git a/src/locks.py b/src/locks.py
index b7c57bf..4d89a07 100644
--- a/src/locks.py
+++ b/src/locks.py
@@ -25,11 +25,11 @@
 #   scemama@irsamc.ups-tlse.fr
 
 
-from .command_line import command_line
+from command_line import command_line
 
-from .irpf90_t import *
-from .util import *
-from .variables import variables
+from irpf90_t import *
+from util import *
+from variables import variables
 FILENAME=irpdir+'irp_locks.irp.F90'
 
 def create():
diff --git a/src/makefile.py b/src/makefile.py
index d9c83ca..5f2e338 100644
--- a/src/makefile.py
+++ b/src/makefile.py
@@ -26,8 +26,8 @@
 
 
 import os,sys
-from . import irpf90_t
-from .command_line import command_line
+import irpf90_t
+from command_line import command_line
 irpdir = irpf90_t.irpdir
 mandir = irpf90_t.mandir
 
@@ -82,12 +82,12 @@ def create_gitignore():
 
 ######################################################################
 def run_ninja():
-    from . import ninja
+    import ninja
     ninja.run()
 
 ######################################################################
 def run_make():
-    from .modules import modules
+    from modules import modules
     mod = []
     for m in list(modules.values()):
       mod.append(m)
diff --git a/src/module.py b/src/module.py
index 55f7d85..bc73af4 100644
--- a/src/module.py
+++ b/src/module.py
@@ -25,12 +25,12 @@
 #   scemama@irsamc.ups-tlse.fr
 
 
-from .irpf90_t import *
-from .variable import *
-from .variables import variables
-from .command_line import command_line
-from . import preprocessed_text
-from .util import *
+from irpf90_t import *
+from variable import *
+from variables import variables
+from command_line import command_line
+import preprocessed_text
+from util import *
 
 class Fmodule(object):
 
@@ -67,7 +67,7 @@ class Fmodule(object):
 
   def variables(self):
     if '_variables' not in self.__dict__:
-      from .variables import variables
+      from variables import variables
       name = self.name
       self._variables = [x for x in variables if variables[x].fmodule == name]
     return self._variables
@@ -119,8 +119,8 @@ class Fmodule(object):
 
   def residual_text(self):
     if '_residual_text' not in self.__dict__:
-      from .variables import build_use, call_provides
-      from .parsed_text import move_to_top
+      from variables import build_use, call_provides
+      from parsed_text import move_to_top
       def remove_providers(text):
         result = []
         inside = False
@@ -215,7 +215,7 @@ class Fmodule(object):
 ######################################################################
 
 if __name__ == '__main__':
-  from .parsed_text import parsed_text
+  from parsed_text import parsed_text
   for filename, text in parsed_text:
     if filename == 'vmc_step.irp.f':
      x = Fmodule(text,filename)
diff --git a/src/modules.py b/src/modules.py
index 9971a67..e016b8d 100644
--- a/src/modules.py
+++ b/src/modules.py
@@ -25,10 +25,10 @@
 #   scemama@irsamc.ups-tlse.fr
 
 
-from .irpf90_t import *
-from .parsed_text import parsed_text
-from .module import Fmodule
-from .util import *
+from irpf90_t import *
+from parsed_text import parsed_text
+from module import Fmodule
+from util import *
 
 ######################################################################
 def create_modules():
diff --git a/src/ninja.py b/src/ninja.py
index 3e08e47..76fd51c 100644
--- a/src/ninja.py
+++ b/src/ninja.py
@@ -26,9 +26,9 @@
 
 
 import os,sys
-from . import irpf90_t
-from .command_line import command_line
-from .modules import modules
+from import irpf90_t
+from command_line import command_line
+from modules import modules
 irpdir = irpf90_t.irpdir
 mandir = irpf90_t.mandir
 irp_id = irpf90_t.irp_id
@@ -257,7 +257,7 @@ veryclean: clean
 
 """.format(irpdir, targets)
 
-    from . import makefile
+    import makefile
     with open(makefile.IRPF90_MAKE,'w') as file:
         file.write(result)
 
diff --git a/src/parsed_text.py b/src/parsed_text.py
index 6a41f18..9540307 100644
--- a/src/parsed_text.py
+++ b/src/parsed_text.py
@@ -25,13 +25,13 @@
 #   scemama@irsamc.ups-tlse.fr
 
 
-from .util import *
-from .irpf90_t import *
-from .variables import variables
-from .preprocessed_text import preprocessed_text
-from .subroutines import subroutines
+from util import *
+from irpf90_t import *
+from variables import variables
+from preprocessed_text import preprocessed_text
+from subroutines import subroutines
 import regexps, re
-from . import error
+import error
 
 vtuple = [(v, variables[v].same_as, variables[v].regexp) for v in list(variables.keys())]
 stuple = [(s, subroutines[s].regexp) for s in list(subroutines.keys())]
@@ -497,7 +497,7 @@ parsed_text = result
 
 
 ######################################################################
-from .command_line import command_line
+from command_line import command_line
 
 def check_opt():
   if not command_line.do_checkopt:
diff --git a/src/preprocessed_text.py b/src/preprocessed_text.py
index 5a71320..81a15f9 100644
--- a/src/preprocessed_text.py
+++ b/src/preprocessed_text.py
@@ -24,11 +24,11 @@
 #   31062 Toulouse Cedex 4
 #   scemama@irsamc.ups-tlse.fr
 
-from .irpf90_t import *
-from .regexps import *
-from . import error
-from .command_line import command_line
-from .util import *
+from irpf90_t import *
+from regexps import *
+import error
+from command_line import command_line
+from util import *
 
 # Local regular expressions
 re_endif = re.compile("end\s+if")
diff --git a/src/profile.py b/src/profile.py
index 3b583b6..70e75af 100644
--- a/src/profile.py
+++ b/src/profile.py
@@ -45,7 +45,7 @@ import subprocess
 import tempfile
 import os
 import threading
-from .irpf90_t import irpdir
+from irpf90_t import irpdir
 
 def build_rdtsc():
   filename = irpdir+"irp_rdtsc.c"
@@ -60,7 +60,7 @@ def build_rdtsc():
   threading.Thread(target=t).start()
 
 def build_module():
-  from .variables import variables
+  from variables import variables
   data = """
 module irp_timer
  double precision :: irp_profile(3,%(n)d) 
diff --git a/src/subroutine.py b/src/subroutine.py
index 218145d..70234f4 100644
--- a/src/subroutine.py
+++ b/src/subroutine.py
@@ -25,9 +25,9 @@
 #   scemama@irsamc.ups-tlse.fr
 
 
-from .irpf90_t import *
-from .util import *
-from . import error
+from irpf90_t import *
+from util import *
+import error
 
 class Sub(object):
 
@@ -75,7 +75,7 @@ class Sub(object):
   ############################################################
   def touches(self):
     if '_touches' not in self.__dict__:
-      from .subroutines import subroutines
+      from subroutines import subroutines
       self._touches = []
       for line in [x for x in self.text if type(x) in [Touch, SoftTouch]]:
         self._touches += line.text.split()[1:]
@@ -89,7 +89,7 @@ class Sub(object):
   ############################################################
   def needs(self):
     if '_needs' not in self.__dict__:
-      from . import parsed_text
+      import parsed_text
     self._needs = make_single(self._needs)
     return self._needs
   needs = property(needs)
@@ -97,7 +97,7 @@ class Sub(object):
   ############################################################
   def to_provide(self):
     if '_to_provide' not in self.__dict__:
-      from . import parsed_text
+      import parsed_text
     return self._to_provide
   to_provide = property(to_provide)
 
@@ -124,8 +124,8 @@ class Sub(object):
 
 ######################################################################
 if __name__ == '__main__':
-  from .preprocessed_text import preprocessed_text
-  from .variables import variables
-  from .subroutines import subroutines
+  from preprocessed_text import preprocessed_text
+  from variables import variables
+  from subroutines import subroutines
   print([variables[x].needs for x in subroutines['full_ci'].needs])
   print(subroutines['full_ci'].calls)
diff --git a/src/subroutines.py b/src/subroutines.py
index aa141f6..c047783 100644
--- a/src/subroutines.py
+++ b/src/subroutines.py
@@ -25,14 +25,14 @@
 #   scemama@irsamc.ups-tlse.fr
 
 
-from .util import *
-from .subroutine import *
-from .variables import variables
-from .variable  import Variable
-from .irpf90_t import *
+from util import *
+from subroutine import *
+from variables import variables
+from variable  import Variable
+from irpf90_t import *
 
 def create_subroutines():
-  from .preprocessed_text import preprocessed_text
+  from preprocessed_text import preprocessed_text
   result = {}
   for filename, text in preprocessed_text:
     buffer = []
diff --git a/src/touches.py b/src/touches.py
index 8f91e02..7060c55 100644
--- a/src/touches.py
+++ b/src/touches.py
@@ -25,10 +25,10 @@
 #   scemama@irsamc.ups-tlse.fr
 
 
-from .irpf90_t import *
-from .util import *
-from .variables import variables
-from .modules import modules
+from irpf90_t import *
+from util import *
+from variables import variables
+from modules import modules
 
 FILENAME=irpdir+'irp_touches.irp.F90'
 
diff --git a/src/util.py b/src/util.py
index c1faf4c..775e64f 100644
--- a/src/util.py
+++ b/src/util.py
@@ -68,7 +68,7 @@ def build_dim_colons(v):
     return "(%s)"%(','.join(x))
 
 
-from . import error
+import error
 def find_subname(line):
   buffer = line.lower
   if not buffer.endswith(')'):
@@ -119,7 +119,7 @@ def put_info(text,filename):
   assert type(text) == list
   if len(text) > 0:
     assert type(text[0]) == tuple
-    from .irpf90_t import Line
+    from irpf90_t import Line
     assert type(text[0][0]) == list
     assert isinstance(text[0][1], Line)
     lenmax = 80 - len(filename)
diff --git a/src/variable.py b/src/variable.py
index cb1853f..e60faba 100644
--- a/src/variable.py
+++ b/src/variable.py
@@ -25,10 +25,10 @@
 #   scemama@irsamc.ups-tlse.fr
 
 
-from .irpf90_t import *
-from .util import *
-from . import error
-from .command_line import command_line
+from irpf90_t import *
+from util import *
+import error
+from command_line import command_line
 
 class Variable(object):
 
@@ -45,7 +45,7 @@ class Variable(object):
   ############################################################
   def is_touched(self):
     if '_is_touched' not in self.__dict__:
-      from .variables import variables
+      from variables import variables
       result = self.is_read
       for i in self.children:
         if variables[i].is_touched:
@@ -66,7 +66,7 @@ class Variable(object):
   ############################################################
   def is_written(self):
     if '_is_written' not in self.__dict__:
-      from .variables import variables
+      from variables import variables
       result = False
       for i in self.parents:
         if variables[i].is_written:
@@ -79,7 +79,7 @@ class Variable(object):
   ############################################################
   def is_read(self):
     if '_is_read' not in self.__dict__:
-      from .variables import variables
+      from variables import variables
       result = False
       for i in self.parents:
         if variables[i].is_read:
@@ -187,7 +187,7 @@ dimension.
       if not self.is_main:
         self._allocate = []
       else:
-        from .variables import variables
+        from variables import variables
         def f(var):
           return variables[var].dim != []
         self._allocate = list(filter ( f, self.others + [self.name] ))
@@ -276,10 +276,10 @@ dimension.
       if not self.is_main:
         self._toucher = []
       else:
-        from .modules import modules
-        from .variables import variables
+        from modules import modules
+        from variables import variables
         if '_needed_by' not in self.__dict__:
-          from . import parsed_text
+          import parsed_text
         parents = self.parents
         parents.sort()
         mods = [variables[x].fmodule for x in parents]
@@ -309,8 +309,8 @@ dimension.
       if not command_line.do_openmp:
         self._locker = []
       else:
-        from .modules import modules
-        from .variables import variables
+        from modules import modules
+        from variables import variables
         name = self.name
         result  = [ "subroutine irp_lock_%s(set)"%(name) ]
         result += [ "  use omp_lib",
@@ -348,8 +348,8 @@ dimension.
         self._reader = []
       else:
         if '_needs' not in self.__dict__:
-          from . import parsed_text
-        from .variables import variables
+          import parsed_text
+        from variables import variables
         name = self.name
         result = [ \
         "subroutine reader_%s(irp_num)"%(name),
@@ -393,9 +393,9 @@ dimension.
       if not self.is_main:
         self._writer = []
       else:
-        from .variables import variables
+        from variables import variables
         if '_needs' not in self.__dict__:
-          from . import parsed_text
+          import parsed_text
         name = self.name
         result = [ \
         "subroutine writer_%s(irp_num)"%(name),
@@ -464,8 +464,8 @@ dimension.
        self._provider = []
      else:
       if '_to_provide' not in self.__dict__:
-        from . import parsed_text
-      from .variables import variables, build_use, call_provides
+        import parsed_text
+      from variables import variables, build_use, call_provides
       name = self.name
       same_as = self.same_as
 
@@ -576,8 +576,8 @@ dimension.
       if not self.is_main:
         self._builder = []
       else:
-        from . import parsed_text
-        from .variables import build_use, call_provides
+        import parsed_text
+        from variables import build_use, call_provides
         for filename,buffer in parsed_text.parsed_text:
           if self.line.filename[0].startswith(filename):
             break
@@ -642,9 +642,9 @@ dimension.
     if '_children' not in self.__dict__:
       if not self.is_main:
         self._children = []
-      from .variables import variables
+      from variables import variables
       if '_needs' not in self.__dict__:
-        from . import parsed_text
+        import parsed_text
       result = []
       for x in self.needs:
         result.append(x)
@@ -664,9 +664,9 @@ dimension.
       if not self.is_main:
         self._parents = []
       else:
-        from .variables import variables
+        from variables import variables
         if '_needed_by' not in self.__dict__:
-          from . import parsed_text
+          import parsed_text
         result = []
         for x in self.needed_by:
           result.append(x)
@@ -682,8 +682,8 @@ dimension.
 
 ######################################################################
 if __name__ == '__main__':
-  from .preprocessed_text import preprocessed_text
-  from .variables import variables
+  from preprocessed_text import preprocessed_text
+  from variables import variables
  #for v in variables.keys():
  #  print v
   def print_dot(x,done):
diff --git a/src/variables.py b/src/variables.py
index 7f6910c..7c8f073 100644
--- a/src/variables.py
+++ b/src/variables.py
@@ -25,14 +25,14 @@
 #   scemama@irsamc.ups-tlse.fr
 
 
-from .variable import *
-from .irpf90_t import *
-from .command_line import command_line
-from .util import *
+from variable import *
+from irpf90_t import *
+from command_line import command_line
+from util import *
 
 ######################################################################
 def create_variables():
-  from .preprocessed_text import preprocessed_text
+  from preprocessed_text import preprocessed_text
   result = {}
   icount = 0
   for filename, text in preprocessed_text: