diff --git a/pycircstat/decorators.py b/pycircstat/decorators.py
index 4862784..021c1c4 100644
--- a/pycircstat/decorators.py
+++ b/pycircstat/decorators.py
@@ -1,6 +1,8 @@
 from __future__ import absolute_import
 
 from functools import wraps
+from inspect import getfullargspec
+import sys
 import numpy as np
 from . import CI
 from decorator import decorator
@@ -36,7 +38,10 @@ def wrapper(f, *args, **kwargs):
 
 
 def get_var(f, varnames, args, kwargs):
-    fvarnames = f.__code__.co_varnames
+    if sys.version_info[0] > 2:
+        fvarnames = getfullargspec(f).args
+    else:
+        fvarnames = f.__code__.co_varnames
 
     var_idx = []
     kwar_keys = []
diff --git a/pycircstat/descriptive.py b/pycircstat/descriptive.py
index dc0d668..3178149 100644
--- a/pycircstat/descriptive.py
+++ b/pycircstat/descriptive.py
@@ -5,7 +5,9 @@
 
 from functools import wraps
 import itertools
+import sys
 from decorator import decorator
+from inspect import getfullargspec
 
 import numpy as np
 from scipy import stats
@@ -34,7 +36,10 @@ def __init__(self, no_bootstrap, scale='linear'):
         self.scale = scale
 
     def _get_var(self, f, what, default, args, kwargs, remove=False):
-        varnames = f.__code__.co_varnames
+        if sys.version_info[0] > 2:
+            varnames = getfullargspec(f).args
+        else:
+            varnames = f.__code__.co_varnames
 
         if what in varnames:
             what_idx = varnames.index(what)