diff --git a/CHANGES.txt b/CHANGES.txt
index c755310..12186ef 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -27,6 +27,10 @@ Bug Fixes
   when the default_timezone is set. These previously had the default
   timezone.
 
+- ``colander.String`` schema type now raises ``colander.Invalid`` when trying
+  to deserialize a non-string item.
+  See https://github.com/Pylons/colander/issues/100
+
 Features
 ~~~~~~~~
 
diff --git a/CONTRIBUTORS.txt b/CONTRIBUTORS.txt
index 120ccfb..afe9392 100644
--- a/CONTRIBUTORS.txt
+++ b/CONTRIBUTORS.txt
@@ -112,3 +112,4 @@ Contributors
 - Doug Latornell, 2013/03/17
 - Clayton Parker, 2013/08/15
 - Brian Sutherland, 2013/08/16
+- Peter Lamut, 2013/08/16
diff --git a/colander/__init__.py b/colander/__init__.py
index c5ef5cb..7051113 100644
--- a/colander/__init__.py
+++ b/colander/__init__.py
@@ -1131,7 +1131,7 @@ class String(SchemaType):
                 else:
                     result = text_type(cstruct)
             else:
-                result = text_type(cstruct)
+                raise Invalid(node)
         except Exception as e:
             raise Invalid(node,
                           _('${val} is not a string: ${err}',
diff --git a/colander/tests/test_colander.py b/colander/tests/test_colander.py
index 9915c25..0a3ca4d 100644
--- a/colander/tests/test_colander.py
+++ b/colander/tests/test_colander.py
@@ -1350,11 +1350,11 @@ class TestString(unittest.TestCase):
         self.assertEqual(result, uni)
 
     def test_deserialize_nonunicode_from_None(self):
+        import colander
         value = object()
         node = DummySchemaNode(None)
         typ = self._makeOne()
-        result = typ.deserialize(node, value)
-        self.assertEqual(result, text_type(value))
+        self.assertRaises(colander.Invalid, typ.deserialize, node, value)
 
     def test_deserialize_from_utf8(self):
         uni = text_(b'\xe3\x81\x82', encoding='utf-8')
@@ -1372,6 +1372,13 @@ class TestString(unittest.TestCase):
         result = typ.deserialize(node, utf16)
         self.assertEqual(result, uni)
 
+    def test_deserialize_from_nonstring_obj(self):
+        import colander
+        value = object()
+        node = DummySchemaNode(None)
+        typ = self._makeOne()
+        self.assertRaises(colander.Invalid, typ.deserialize, node, value)
+
     def test_serialize_null(self):
         from colander import null
         node = DummySchemaNode(None)