diff --git a/wsme/rest/json.py b/wsme/rest/json.py
index abe3d4a..07448c6 100644
--- a/wsme/rest/json.py
+++ b/wsme/rest/json.py
@@ -156,6 +156,8 @@ def fromjson(datatype, value):
 def array_fromjson(datatype, value):
     if value is None:
         return None
+    if not isinstance(value, list):
+        raise ValueError("Value not a valid list: %s" % value)
     return [fromjson(datatype.item_type, item) for item in value]
 
 
@@ -163,6 +165,8 @@ def array_fromjson(datatype, value):
 def dict_fromjson(datatype, value):
     if value is None:
         return None
+    if not isinstance(value, dict):
+        raise ValueError("Value not a valid dict: %s" % value)
     return dict((
         (fromjson(datatype.key_type, item[0]),
             fromjson(datatype.value_type, item[1]))
diff --git a/wsme/tests/test_restjson.py b/wsme/tests/test_restjson.py
index 23731d6..8099ff1 100644
--- a/wsme/tests/test_restjson.py
+++ b/wsme/tests/test_restjson.py
@@ -11,7 +11,8 @@ except:
 
 from wsme.rest.json import fromjson, tojson, parse
 from wsme.utils import parse_isodatetime, parse_isotime, parse_isodate
-from wsme.types import isarray, isdict, isusertype, register_type, UserType
+from wsme.types import isarray, isdict, isusertype, register_type
+from wsme.types import UserType, ArrayType, DictType
 from wsme.rest import expose, validate
 from wsme.exc import ClientSideError, InvalidInput
 
@@ -325,6 +326,28 @@ class TestRestJson(wsme.tests.protocol.RestOnlyProtocolTestCase):
         j = parse('{"a": "2011-01-01"}', {'a': datetime.date}, False)
         assert isinstance(j['a'], datetime.date)
 
+    def test_invalid_list_fromjson(self):
+        jlist = "invalid"
+        try:
+            parse('{"a": "%s"}' % jlist, {'a': ArrayType(str)}, False)
+            assert False
+        except Exception as e:
+            assert isinstance(e, InvalidInput)
+            assert e.fieldname == 'a'
+            assert e.value == jlist
+            assert e.msg == "Value not a valid list: %s" % jlist
+
+    def test_invalid_dict_fromjson(self):
+        jdict = "invalid"
+        try:
+            parse('{"a": "%s"}' % jdict, {'a': DictType(str, str)}, False)
+            assert False
+        except Exception as e:
+            assert isinstance(e, InvalidInput)
+            assert e.fieldname == 'a'
+            assert e.value == jdict
+            assert e.msg == "Value not a valid dict: %s" % jdict
+
     def test_invalid_date_fromjson(self):
         jdate = "2015-01-invalid"
         try: