diff --git a/py/_code/_assertionnew.py b/py/_code/_assertionnew.py
index 192eecfce..2c40a93dc 100644
--- a/py/_code/_assertionnew.py
+++ b/py/_code/_assertionnew.py
@@ -184,7 +184,7 @@ class DebugInterpreter(ast.NodeVisitor):
                 break
             left_explanation, left_result = next_explanation, next_result
         if self._pytesthook:
-            hook_result = self._pytesthook.pytest_assert_compare(
+            hook_result = self._pytesthook.pytest_assert_binrepr(
                 op=op_symbol, left=left_result, right=next_result)
             if hook_result:
                 for new_expl in hook_result:
diff --git a/py/_plugin/hookspec.py b/py/_plugin/hookspec.py
index f295211cd..9f34c4598 100644
--- a/py/_plugin/hookspec.py
+++ b/py/_plugin/hookspec.py
@@ -127,13 +127,14 @@ def pytest_sessionfinish(session, exitstatus):
 # hooks for customising the assert methods
 # -------------------------------------------------------------------------
 
-def pytest_assert_compare(op, left, right):
-    """Customise compare assertion
+def pytest_assert_binrepr(op, left, right):
+    """Customise explanation for binary operators
 
-    Return None or an empty list for no custom compare, otherwise
+    Return None or an empty list for no custom explanation, otherwise
     return a list of strings.  The strings will be joined by newlines
-    but any newlines *in* as string will be escaped.  Note that all
-    but the first line will be indented sligthly.
+    but any newlines *in* a string will be escaped.  Note that all but
+    the first line will be indented sligthly, the intention is for the
+    first line to be a summary.
     """
 
 # -------------------------------------------------------------------------
diff --git a/py/_plugin/pytest_assertion.py b/py/_plugin/pytest_assertion.py
index 2816671ab..347f7edb7 100644
--- a/py/_plugin/pytest_assertion.py
+++ b/py/_plugin/pytest_assertion.py
@@ -33,32 +33,32 @@ def warn_about_missing_assertion():
                              " (are you using python -O?)")
 
 
-def pytest_assert_compare(op, left, right):
-    """Make a specialised explanation for comapare equal"""
-    if type(left) != type(right):
-        return None
-
+def pytest_assert_binrepr(op, left, right):
+    """Make specialised explanations for some operators/operands"""
     left_repr = py.io.saferepr(left, maxsize=30)
     right_repr = py.io.saferepr(right, maxsize=30)
     summary = '%s %s %s' % (left_repr, op, right_repr)
 
-    issquence = lambda x: isinstance(x, (list, tuple))
+    issequence = lambda x: isinstance(x, (list, tuple))
     istext = lambda x: isinstance(x, basestring)
     isdict = lambda x: isinstance(x, dict)
-    isset = lambda: isinstance(left, set)
+    isset = lambda x: isinstance(x, set)
 
     explanation = None
     if op == '==':
-        if istext(left):
+        if istext(left) and istext(right):
             explanation = [line.strip('\n') for line in
                            py.std.difflib.ndiff(left.splitlines(),
                                                 right.splitlines())]
-        elif issquence(left):
+        elif issequence(left) and issequence(right):
             explanation = _compare_eq_sequence(left, right)
-        elif isset():
+        elif isset(left) and isset(right):
             explanation = _compare_eq_set(left, right)
-        elif isdict(left):
+        elif isdict(left) and isdict(right):
             explanation = _pprint_diff(left, right)
+    elif op == 'in':
+        # XXX
+        pass
 
     if not explanation:
         return None
diff --git a/testing/plugin/test_pytest_assertion.py b/testing/plugin/test_pytest_assertion.py
index 596de0050..81796dd12 100644
--- a/testing/plugin/test_pytest_assertion.py
+++ b/testing/plugin/test_pytest_assertion.py
@@ -77,17 +77,17 @@ def test_traceback_failure(testdir):
     ])
 
 
-def test_pytest_assert_compare_called(monkeypatch, hook):
+def test_pytest_assert_binrepr_called(monkeypatch, hook):
     monkeypatch.setattr(py._plugin.pytest_assertion,
-                        'pytest_assert_compare', hook)
+                        'pytest_assert_binrepr', hook)
     interpret('assert 0 == 1', getframe())
     assert hook.called
 
 
-def test_pytest_assert_compare_args(monkeypatch, hook):
+def test_pytest_assert_binrepr_args(monkeypatch, hook):
     print hook.called
     monkeypatch.setattr(py._plugin.pytest_assertion,
-                        'pytest_assert_compare', hook)
+                        'pytest_assert_binrepr', hook)
     interpret('assert [0, 1] == [0, 2]', getframe())
     print hook.called
     print hook.left
@@ -99,32 +99,32 @@ def test_pytest_assert_compare_args(monkeypatch, hook):
 
 class TestAssertCompare:
     def test_different_types(self):
-        assert plugin.pytest_assert_compare('==', [0, 1], 'foo') is None
+        assert plugin.pytest_assert_binrepr('==', [0, 1], 'foo') is None
 
     def test_summary(self):
-        summary = plugin.pytest_assert_compare('==', [0, 1], [0, 2])[0]
+        summary = plugin.pytest_assert_binrepr('==', [0, 1], [0, 2])[0]
         assert len(summary) < 65
 
     def test_text_diff(self):
-        diff = plugin.pytest_assert_compare('==', 'spam', 'eggs')[1:]
+        diff = plugin.pytest_assert_binrepr('==', 'spam', 'eggs')[1:]
         assert '- spam' in diff
         assert '+ eggs' in diff
 
     def test_multiline_text_diff(self):
         left = 'foo\nspam\nbar'
         right = 'foo\neggs\nbar'
-        diff = plugin.pytest_assert_compare('==', left, right)
+        diff = plugin.pytest_assert_binrepr('==', left, right)
         assert '- spam' in diff
         assert '+ eggs' in diff
 
     def test_list(self):
-        expl = plugin.pytest_assert_compare('==', [0, 1], [0, 2])
+        expl = plugin.pytest_assert_binrepr('==', [0, 1], [0, 2])
         assert len(expl) > 1
 
     def test_dict(self):
-        expl = plugin.pytest_assert_compare('==', {'a': 0}, {'a': 1})
+        expl = plugin.pytest_assert_binrepr('==', {'a': 0}, {'a': 1})
         assert len(expl) > 1
 
     def test_set(self):
-        expl = plugin.pytest_assert_compare('==', set([0, 1]), set([0, 2]))
+        expl = plugin.pytest_assert_binrepr('==', set([0, 1]), set([0, 2]))
         assert len(expl) > 1