diff --git a/CHANGELOG b/CHANGELOG
index ad1799b11..4478439c6 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -18,6 +18,10 @@
 - Fix issue #411: Add __eq__ method to assertion comparison example.
   Thanks Ben Webb.
 
+- fix issue 877: propperly handle assertion explanations with non-ascii repr
+  Thanks Mathieu Agopian for the report and Ronny Pfannschmidt for the PR.
+
+
 2.8.0
 -----------------------------
 
diff --git a/_pytest/assertion/util.py b/_pytest/assertion/util.py
index fb5f9be0e..ca54f1692 100644
--- a/_pytest/assertion/util.py
+++ b/_pytest/assertion/util.py
@@ -129,7 +129,16 @@ def assertrepr_compare(config, op, left, right):
     width = 80 - 15 - len(op) - 2  # 15 chars indentation, 1 space around op
     left_repr = py.io.saferepr(left, maxsize=int(width/2))
     right_repr = py.io.saferepr(right, maxsize=width-len(left_repr))
-    summary = u('%s %s %s') % (left_repr, op, right_repr)
+
+    # the re-encoding is needed for python2 repr
+    # with non-ascii characters (see issue 877)
+    def ecu(s):
+        try:
+            return u(s, 'utf-8', 'replace')
+        except TypeError:
+            return s
+
+    summary = u('%s %s %s') % (ecu(left_repr), op, ecu(right_repr))
 
     issequence = lambda x: (isinstance(x, (list, tuple, Sequence))
                             and not isinstance(x, basestring))
diff --git a/testing/test_assertion.py b/testing/test_assertion.py
index a25788307..914feddf7 100644
--- a/testing/test_assertion.py
+++ b/testing/test_assertion.py
@@ -231,6 +231,17 @@ class TestAssert_reprcompare:
         assert expl[1] == py.builtin._totext('- £€', 'utf-8')
         assert expl[2] == py.builtin._totext('+ £', 'utf-8')
 
+    def test_nonascii_text(self):
+        """
+        :issue: 877
+        non ascii python2 str caused a UnicodeDecodeError
+        """
+        class A(str):
+            def __repr__(self):
+                return '\xff'
+        expl = callequal(A(), '1')
+        assert expl
+
     def test_mojibake(self):
         # issue 429
         left = 'e'