diff --git a/bottle.py b/bottle.py
index ee4398ea2..f85fd0a13 100644
--- a/bottle.py
+++ b/bottle.py
@@ -42,6 +42,7 @@
 import base64, cgi, email.utils, functools, hmac, imp, itertools, mimetypes,\
         os, re, sys, tempfile, threading, time, warnings
 
+from types import FunctionType
 from datetime import date as datedate, datetime, timedelta
 from tempfile import TemporaryFile
 from traceback import format_exc, print_exc
@@ -543,7 +544,17 @@ def get_undecorated_callback(self):
         func = getattr(func, '__func__' if py3k else 'im_func', func)
         closure_attr = '__closure__' if py3k else 'func_closure'
         while hasattr(func, closure_attr) and getattr(func, closure_attr):
-            func = getattr(func, closure_attr)[0].cell_contents
+            attributes = getattr(func, closure_attr)
+            func = attributes[0].cell_contents
+
+            # in case of decorators with multiple arguments
+            if not isinstance(func, FunctionType) and func is not None:
+                # pick first FunctionType instance from multiple arguments
+                func = filter(
+                    lambda x: isinstance(x, FunctionType),
+                    map(lambda x: x.cell_contents, attributes)
+                )
+                func = list(func)[0]  # py3 support
         return func
 
     def get_callback_args(self):
diff --git a/test/test_route.py b/test/test_route.py
index 66709cb5c..237d3c7f2 100644
--- a/test/test_route.py
+++ b/test/test_route.py
@@ -28,3 +28,23 @@ def w():
         self.assertEqual(route.get_undecorated_callback(), x)
         self.assertEqual(set(route.get_callback_args()), set(['a', 'b']))
 
+    def test_callback_inspection_multiple_args(self):
+        # decorator with argument, modifying kwargs
+        def d2(f="1"):
+            def d(fn):
+                def w(*args, **kwargs):
+                    # modification of kwargs WITH the decorator argument
+                    # is necessary requirement for the error
+                    kwargs["a"] = f
+                    return fn(*args, **kwargs)
+                return w
+            return d
+
+        @d2(f='foo')
+        def x(a, b):
+            return
+
+        route = bottle.Route(None, None, None, x)
+
+        # triggers the "TypeError: 'foo' is not a Python function"
+        self.assertEqual(set(route.get_callback_args()), set(['a', 'b']))