diff --git a/CHANGES.txt b/CHANGES.txt
index 8a3f1217..c9612683 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -9,6 +9,8 @@ CHANGELOG
 Breaking changes
 
 - Get rid of Buildout files (#369)
+- ``request.errors.add()`` now only accepts one of ``header``, ``body``, ``url``,
+  ``querystring`` as first argument (fixes #99)
 
 
 1.2.1 (2016-03-15)
diff --git a/cornice/errors.py b/cornice/errors.py
index 60d254d7..ed3534d0 100644
--- a/cornice/errors.py
+++ b/cornice/errors.py
@@ -17,6 +17,10 @@ def __init__(self, request=None, status=400):
 
     def add(self, location, name=None, description=None, **kw):
         """Registers a new error."""
+        allowed = ('body', 'querystring', 'url', 'header')
+        if location not in allowed:
+            raise ValueError('%r not in %s' % (location, allowed))
+
         self.append(dict(
             location=location,
             name=name,
diff --git a/cornice/tests/test_errors.py b/cornice/tests/test_errors.py
new file mode 100644
index 00000000..b39f9b48
--- /dev/null
+++ b/cornice/tests/test_errors.py
@@ -0,0 +1,12 @@
+from cornice.tests.support import TestCase
+
+from cornice.errors import Errors
+
+
+class TestErrorsHelper(TestCase):
+    def setUp(self):
+        self.errors = Errors()
+
+    def test_raises_an_exception_when_location_is_unsupported(self):
+        with self.assertRaises(ValueError):
+            self.errors.add('something')
diff --git a/docs/source/validation.rst b/docs/source/validation.rst
index de096d7b..7bfde625 100644
--- a/docs/source/validation.rst
+++ b/docs/source/validation.rst
@@ -299,7 +299,7 @@ This means something like this::
         def validate_it(request):
             # pseudo-code validation logic
             if whatever is wrong:
-                request.errors.add('something')
+                request.errors.add('body', description="Something is wrong")
 
     @service.get(klass=MyClass, validators=('validate_it',))
     def view(request):