diff --git a/setup.py b/setup.py
index b121130..20a39ef 100644
--- a/setup.py
+++ b/setup.py
@@ -13,7 +13,7 @@
 setup(
         name="yccp",
         version=".".join(map(str, __version__)),
-        install_requires=["PyYAML>=3.12"],
+        install_requires=["PyYAML>=3.12", "future"],
         packages=["yccp", "yccp.cli", "yccp.sweeps"],
         entry_points={
             "console_scripts" : [
diff --git a/yccp/meta.py b/yccp/meta.py
index dcd3772..99145c7 100644
--- a/yccp/meta.py
+++ b/yccp/meta.py
@@ -98,12 +98,12 @@ def __new__(mcs, name, bases, dct):
                             base.__name__))
                     del to_update[to_delete]
 
-            for k,v in to_update.iteritems():
+            for k,v in to_update.items():
                 if k in all_nonrec_updates:
                     updated_defaults.setdefault(k, {}).update(v)
                 else:
                     updated_defaults[k] = v
-        for k,v in dct.get(mcs.attr_defaults, {}).iteritems():
+        for k,v in dct.get(mcs.attr_defaults, {}).items():
             if k in all_nonrec_updates:
                 updated_defaults.setdefault(k, {}).update(v)
             else:
@@ -173,7 +173,7 @@ def _get_updated_parameters(cls, parameters):
         cls, cls.__metaclass__.attr_nonrec_update, set())
 
     # update the default parameters with whatever was proved
-    for k, v in copy.deepcopy(parameters).iteritems():
+    for k, v in copy.deepcopy(parameters).items():
         if k in prms:
             if isinstance(v, dict)\
                     and k not in not_recursively_updated_attributes:
diff --git a/yccp/prelude.py b/yccp/prelude.py
index aa1b26f..13c8064 100644
--- a/yccp/prelude.py
+++ b/yccp/prelude.py
@@ -14,6 +14,7 @@
         "load",
     ]
 
+from builtins import str
 
 import numpy as np
 import yaml
@@ -109,7 +110,7 @@ def disable(self):
     def eval(self, value):
         if isinstance(value, (RawExpression, RawPreludeEntry)):
             value = value.expression
-        if not isinstance(value, basestring):
+        if not isinstance(value, str):
             return value
         eval_globals = {"np": np}
         eval_locals = {
@@ -146,7 +147,7 @@ def __call__(self, loader, node):
 yaml.add_representer(RawExpression,
                      lambda dumper, re: re.dump(dumper),
                      Dumper=YccpDumper)
-yaml.add_representer(unicode, lambda dumper, value:
+yaml.add_representer(str, lambda dumper, value:
                      dumper.represent_scalar(u'tag:yaml.org,2002:str', value),
                      Dumper=YccpDumper)
 
@@ -231,7 +232,7 @@ def load_data_with_prelude(obj, name_prelude=default_prelude_attr, **kwargs):
                 "of dictionaries".format(name_prelude_found))
 
         for dct in prelude:
-            for k, v in dct.iteritems():
+            for k, v in dct.items():
                 evaluate_expression.prelude_add(
                     k, evaluate_expression.eval(v))
 
diff --git a/yccp/utils.py b/yccp/utils.py
index 381da3a..d66d74e 100644
--- a/yccp/utils.py
+++ b/yccp/utils.py
@@ -124,7 +124,7 @@ def update_dict_recursively(d, u):
     """
         Dictionary d with the contents from u in recursive manner.
     """
-    for k, v in copy.deepcopy(u).iteritems():
+    for k, v in copy.deepcopy(u).items():
         if isinstance(v, c.Mapping):
             if k in d and not isinstance(d.get(k), c.Mapping):
                 raise ValueError(