diff --git a/CHANGELOG b/CHANGELOG
index 06f9fca05..d3da98594 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -5,6 +5,9 @@ Unreleased
 
 - removed outdated japanese docs from source tree.
 
+- Escape % character in the assertion message.
+
+
 2.6.3
 -----------
 
diff --git a/_pytest/assertion/rewrite.py b/_pytest/assertion/rewrite.py
index 18df7791e..57edcd487 100644
--- a/_pytest/assertion/rewrite.py
+++ b/_pytest/assertion/rewrite.py
@@ -373,7 +373,7 @@ def _format_assertmsg(obj):
         t = py.builtin.text
     else:
         t = py.builtin.bytes
-    s = s.replace(t("\n"), t("\n~"))
+    s = s.replace(t("\n"), t("\n~")).replace(t("%"), t("%%"))
     if is_repr:
         s = s.replace(t("\\n"), t("\n~"))
     return s
diff --git a/testing/test_assertmessage.py b/testing/test_assertmessage.py
deleted file mode 100644
index ca67ff55a..000000000
--- a/testing/test_assertmessage.py
+++ /dev/null
@@ -1,18 +0,0 @@
-
-def test_assert_message_fail():
-    '''
-    Check if custom message with % sign do not raise ValueError
-    Later test can be parametrized with other problematic chars
-    '''
-
-    MESSAGE = 'Message with %'
-       
-    try:
-        assert False, MESSAGE
-    except ValueError, ve:
-        assert False, 'ValueError was raised with the following message: ' \
-            + ve.message
-    except AssertionError, ae:
-        assert MESSAGE == ae.message, 'Assertion message: ' + ae.message \
-            + ' is different than expected: ' + MESSAGE
-   
\ No newline at end of file
diff --git a/testing/test_assertrewrite.py b/testing/test_assertrewrite.py
index 9d69b5f49..225608281 100644
--- a/testing/test_assertrewrite.py
+++ b/testing/test_assertrewrite.py
@@ -172,6 +172,18 @@ class TestAssertionRewrite:
             "*assert 1 == 2*",
         ])
 
+    def test_assertion_message_escape(self, testdir):
+        testdir.makepyfile("""
+            def test_foo():
+                assert 1 == 2, 'To be escaped: %'
+        """)
+        result = testdir.runpytest()
+        assert result.ret == 1
+        result.stdout.fnmatch_lines([
+            "*AssertionError: To be escaped: %",
+            "*assert 1 == 2",
+        ])
+
     def test_boolop(self):
         def f():
             f = g = False