diff --git a/django_tables2/tables.py b/django_tables2/tables.py
index 2758ad4..01a0671 100644
--- a/django_tables2/tables.py
+++ b/django_tables2/tables.py
@@ -6,6 +6,7 @@ from .rows import BoundRows
 from .utils import (Accessor, AttributeDict, build_request, cached_property,
                     computed_values, OrderBy, OrderByTuple, segment, Sequence)
 import copy
+import sys
 from django.core.paginator       import Paginator
 from django.db.models.fields     import FieldDoesNotExist
 from django.utils.datastructures import SortedDict
@@ -34,12 +35,15 @@ class TableData(object):
             self.queryset = data
         # otherwise it must be convertable to a list
         else:
-            try:
+            # do some light validation
+            if hasattr(data, '__iter__') or (hasattr(data, '__len__') and hasattr(data, '__getitem__')):
                 self.list = list(data)
-            except:
-                raise ValueError('data must be QuerySet-like (have count and '
-                                 'order_by) or support list(data) -- %s has '
-                                 'neither' % type(data).__name__)
+            else:
+                raise ValueError(
+                    'data must be QuerySet-like (have count and '
+                    'order_by) or support list(data) -- %s has '
+                    'neither' % type(data).__name__
+                )
 
     def __len__(self):
         if not hasattr(self, "_length"):
diff --git a/tests/core.py b/tests/core.py
index 0a4dce2..66351e2 100644
--- a/tests/core.py
+++ b/tests/core.py
@@ -178,7 +178,30 @@ def should_support_haystack_data_source():
 
     table = PersonTable(SearchQuerySet().all())
     table.as_html()
+
+
+@core.test
+def data_validation():
+    with raises(ValueError):
+        table = OrderedTable(None)
+    
+    class Bad:
+        def __len__(self):
+            pass
+      
+    with raises(ValueError):
+        table = OrderedTable(Bad())
 
+    class Ok:
+        def __len__(self):
+            return 1
+        def __getitem__(self, pos):
+            if pos != 0:
+                raise IndexError()
+            return {'a': 1}
+    
+    table = OrderedTable(Ok())
+    assert len(table.rows) == 1
 
 @core.test
 def ordering():