diff --git a/tests/pecantest/test/controllers/ws.py b/tests/pecantest/test/controllers/ws.py
index acb4402..9036bcd 100644
--- a/tests/pecantest/test/controllers/ws.py
+++ b/tests/pecantest/test/controllers/ws.py
@@ -119,3 +119,7 @@ class AuthorsController(RestController):
     @wsmeext.pecan.wsexpose(None, int)
     def delete(self, author_id):
         print("Deleting", author_id)
+
+    @wsmeext.pecan.wsexpose(Book, int, body=Author)
+    def put(self, author_id, author=None):
+        return author
diff --git a/tests/pecantest/test/tests/test_ws.py b/tests/pecantest/test/tests/test_ws.py
index ab274cd..6002796 100644
--- a/tests/pecantest/test/tests/test_ws.py
+++ b/tests/pecantest/test/tests/test_ws.py
@@ -69,6 +69,19 @@ class TestWS(FunctionalTest):
         assert a['id'] == 10
         assert a['firstname'] == 'test'
 
+    def test_put_parameter_validate(self):
+        res = self.app.put(
+            '/authors/foobar', '{"firstname": "test"}',
+            headers={"Content-Type": "application/json"},
+            expect_errors=True
+        )
+        self.assertEqual(res.status_int, 400)
+        a = json.loads(res.body.decode('utf-8'))
+        self.assertEqual(
+            a['faultstring'],
+            "Invalid input for field/attribute author_id. "
+            "Value: 'foobar'. unable to convert to int")
+
     def test_clientsideerror(self):
         expected_status_code = 400
         expected_status = http_response_messages[expected_status_code]
diff --git a/wsme/rest/args.py b/wsme/rest/args.py
index 42ad040..6ab9403 100644
--- a/wsme/rest/args.py
+++ b/wsme/rest/args.py
@@ -4,7 +4,7 @@ import re
 
 from simplegeneric import generic
 
-from wsme.exc import ClientSideError, UnknownArgument
+from wsme.exc import ClientSideError, UnknownArgument, InvalidInput
 
 from wsme.types import iscomplex, list_attributes, Unset
 from wsme.types import UserType, ArrayType, DictType, File
@@ -168,7 +168,13 @@ def dict_from_params(datatype, params, path, hit_paths):
 def args_from_args(funcdef, args, kwargs):
     newargs = []
     for argdef, arg in zip(funcdef.arguments[:len(args)], args):
-        newargs.append(from_param(argdef.datatype, arg))
+        try:
+            newargs.append(from_param(argdef.datatype, arg))
+        except Exception:
+            raise InvalidInput(
+                argdef.name,
+                arg,
+                "unable to convert to %s" % argdef.datatype.__name__)
     newkwargs = {}
     for argname, value in kwargs.items():
         newkwargs[argname] = from_param(