diff --git a/autograd/core.py b/autograd/core.py
index 6d7292294..89b2d78f8 100644
--- a/autograd/core.py
+++ b/autograd/core.py
@@ -74,13 +74,14 @@ def __call__(self, *args, **kwargs):
 
     def vjp(self, argnum, outgrad, ans, vs, gvs, args, kwargs):
         try:
-            return self.vjps[argnum](outgrad, ans, vs, gvs, *args, **kwargs)
+            vjp = self.vjps[argnum]
         except KeyError:
             if self.vjps == {}:
                 errstr = "Gradient of {0} not yet implemented."
             else:
                 errstr = "Gradient of {0} w.r.t. arg number {1} not yet implemented."
             raise NotImplementedError(errstr.format(self.fun.__name__, argnum))
+        return vjp(outgrad, ans, vs, gvs, *args, **kwargs)
 
     def defvjp(self, vjpmaker, argnum=0):
         vjpmaker.__name__ = "VJP_{}_of_{}".format(argnum, self.__name__)