diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index 5dcd546c0..643aa762f 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -55,8 +55,10 @@ def is_simple_callable(obj):
 
     if not (function or method):
         return False
-
-    args, _, _, defaults = inspect.getargspec(obj)
+    if six.PY2:
+        args, _, _, defaults = inspect.getargspec(obj)
+    else:
+        args, _, _, defaults, _, _, _ = inspect.getfullargspec(obj)
     len_args = len(args) if function else len(args) - 1
     len_defaults = len(defaults) if defaults else 0
     return len_args <= len_defaults