diff --git a/changelog.d/951.change.rst b/changelog.d/951.change.rst
index 24303f6a9..6ded5fe7b 100644
--- a/changelog.d/951.change.rst
+++ b/changelog.d/951.change.rst
@@ -1,3 +1 @@
-The error signature of _InValidator has been completed,
-it now includes the attribute,
-options and value as proclaimed in the docstring of _in().
+``attrs.validators._in()``'s ``ValueError`` is not missing the attribute, expected options, and the value it got anymore.
diff --git a/docs/api.rst b/docs/api.rst
index 74c482bc3..37392ee49 100644
--- a/docs/api.rst
+++ b/docs/api.rst
@@ -566,24 +566,24 @@ All objects from ``attrs.validators`` are also available from ``attr.validators`
 
    .. doctest::
 
-       >>> import enum
-       >>> class State(enum.Enum):
-       ...     ON = "on"
-       ...     OFF = "off"
-       >>> @attrs.define
-       ... class C:
-       ...     state = attrs.field(validator=attrs.validators.in_(State))
-       ...     val = attrs.field(validator=attrs.validators.in_([1, 2, 3]))
-       >>> C(State.ON, 1)
-       C(state=<State.ON: 'on'>, val=1)
-       >>> C("on", 1)
-       Traceback (most recent call last):
-          ...
-       ValueError: 'state' must be in <enum 'State'> (got 'on')
-       >>> C(State.ON, 4)
-       Traceback (most recent call last):
-          ...
-       ValueError: 'val' must be in [1, 2, 3] (got 4)
+      >>> import enum
+      >>> class State(enum.Enum):
+      ...     ON = "on"
+      ...     OFF = "off"
+      >>> @attrs.define
+      ... class C:
+      ...     state = attrs.field(validator=attrs.validators.in_(State))
+      ...     val = attrs.field(validator=attrs.validators.in_([1, 2, 3]))
+      >>> C(State.ON, 1)
+      C(state=<State.ON: 'on'>, val=1)
+      >>> C("on", 1)
+      Traceback (most recent call last):
+         ...
+      ValueError: 'state' must be in <enum 'State'> (got 'on'), Attribute(name='state', default=NOTHING, validator=<in_ validator with options <enum 'State'>>, repr=True, eq=True, eq_key=None, order=True, order_key=None, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False, inherited=False, on_setattr=None), <enum 'State'>, 'on')
+      >>> C(State.ON, 4)
+      Traceback (most recent call last):
+      ...
+      ValueError: 'val' must be in [1, 2, 3] (got 4), Attribute(name='val', default=NOTHING, validator=<in_ validator with options [1, 2, 3]>, repr=True, eq=True, eq_key=None, order=True, order_key=None, hash=None, init=True, metadata=mappingproxy({}), type=None, converter=None, kw_only=False, inherited=False, on_setattr=None), [1, 2, 3], 4)
 
 .. autofunction:: attrs.validators.provides
 
diff --git a/src/attr/validators.py b/src/attr/validators.py
index 3a4e72823..eece517da 100644
--- a/src/attr/validators.py
+++ b/src/attr/validators.py
@@ -325,6 +325,10 @@ def in_(options):
        got.
 
     .. versionadded:: 17.1.0
+    .. versionchanged:: 22.1.0
+       The ValueError was incomplete until now and only contained the human
+       readable error message. Now it contains all the information that has
+       been promised since 17.1.0.
     """
     return _InValidator(options)
 
diff --git a/tests/test_validators.py b/tests/test_validators.py
index 3bec62b03..51fe2f41e 100644
--- a/tests/test_validators.py
+++ b/tests/test_validators.py
@@ -469,8 +469,10 @@ def test_fail(self):
         """
         v = in_([1, 2, 3])
         a = simple_attr("test")
+
         with pytest.raises(ValueError) as e:
             v(None, a, None)
+
         assert (
             "'test' must be in [1, 2, 3] (got None)",
             a,