diff --git a/praw/decorator_helpers.py b/praw/decorator_helpers.py
index 413cbfb02..375dca8ff 100644
--- a/praw/decorator_helpers.py
+++ b/praw/decorator_helpers.py
@@ -1,4 +1,5 @@
 """Internal helper functions used by praw.decorators."""
+import inspect
 from requests.compat import urljoin
 import six
 import sys
@@ -23,3 +24,15 @@ def _is_mod_of_all(user, subreddit):
     mod_subs = user.get_cached_moderated_reddits()
     subs = six.text_type(subreddit).lower().split('+')
     return all(sub in mod_subs for sub in subs)
+
+
+def _make_func_args(function):
+    if six.PY3 and not hasattr(sys, 'pypy_version_info'):
+        # CPython3 uses inspect.signature(), not inspect.getargspec()
+        # see #551 and #541 for more info
+        func_items = inspect.signature(function).parameters.items()
+        func_args = [name for name, param in func_items
+                     if param.kind == param.POSITIONAL_OR_KEYWORD]
+    else:
+        func_args = inspect.getargspec(function).args
+    return func_args
diff --git a/praw/decorators.py b/praw/decorators.py
index 41d366f71..d28e4ce8e 100644
--- a/praw/decorators.py
+++ b/praw/decorators.py
@@ -24,11 +24,14 @@
 from __future__ import print_function, unicode_literals
 
 import decorator
-import inspect
 import six
 import sys
 from functools import wraps
-from praw.decorator_helpers import _get_captcha, _is_mod_of_all
+from praw.decorator_helpers import (
+    _get_captcha,
+    _is_mod_of_all,
+    _make_func_args
+)
 from praw import errors
 from warnings import simplefilter, warn
 
@@ -48,7 +51,7 @@ def alias_function(function, class_name):
     """
     @wraps(function)
     def wrapped(self, *args, **kwargs):
-        func_args = inspect.getargspec(function).args
+        func_args = _make_func_args(function)
         if 'subreddit' in func_args and func_args.index('subreddit') != 1:
             # Only happens for search
             kwargs['subreddit'] = self
@@ -164,9 +167,9 @@ def require_captcha(function, *args, **kwargs):
                 # *args currently contains a None where the captcha answer
                 # needs to go. If we put the captcha in the **kwargs,
                 # we get a TypeError for having two values of the same param.
-                func_args = inspect.getargspec(function)
-                if 'captcha' in func_args.args:
-                    captcha_index = func_args.args.index('captcha')
+                func_args = _make_func_args(function)
+                if 'captcha' in func_args:
+                    captcha_index = func_args.index('captcha')
                     args = list(args)
                     args[captcha_index] = captcha_answer
                 else:
diff --git a/tests/test_decorators.py b/tests/test_decorators.py
index fdc299318..1b62736b6 100644
--- a/tests/test_decorators.py
+++ b/tests/test_decorators.py
@@ -1,6 +1,7 @@
 from __future__ import print_function, unicode_literals
 
 import unittest
+from praw.decorator_helpers import _make_func_args
 from praw.decorators import restrict_access
 
 
@@ -8,3 +9,15 @@ class DecoratorTest(unittest.TestCase):
     def test_require_access_failure(self):
         self.assertRaises(TypeError, restrict_access, scope=None,
                           oauth_only=True)
+
+    def test_make_func_args(self):
+        def foo(arg1, arg2, arg3):
+            pass
+
+        def bar(arg1, arg2, arg3, *args, **kwargs):
+            pass
+
+        arglist = ['arg1', 'arg2', 'arg3']
+
+        self.assertEqual(_make_func_args(foo), arglist)
+        self.assertEqual(_make_func_args(bar), arglist)