diff --git a/newsfragments/3564.minor b/newsfragments/3564.minor
new file mode 100644
index 000000000..e69de29bb
diff --git a/setup.py b/setup.py
index c26805684..345d6aa08 100644
--- a/setup.py
+++ b/setup.py
@@ -111,7 +111,9 @@ install_requires = [
 
     # Eliot is contemplating dropping Python 2 support.  Stick to a version we
     # know works on Python 2.7.
-    "eliot ~= 1.7",
+    "eliot ~= 1.7 ; python_version < '3.0'",
+    # On Python 3, we want a new enough version to support custom JSON encoders.
+    "eliot >= 1.13.0 ; python_version > '3.0'",
 
     # Pyrsistent 0.17.0 (which we use by way of Eliot) has dropped
     # Python 2 entirely; stick to the version known to work for us.
diff --git a/src/allmydata/test/eliotutil.py b/src/allmydata/test/eliotutil.py
index 0c72502a7..88b4ec90e 100644
--- a/src/allmydata/test/eliotutil.py
+++ b/src/allmydata/test/eliotutil.py
@@ -31,6 +31,9 @@ from twisted.internet.defer import (
     maybeDeferred,
 )
 
+from ..util.jsonbytes import BytesJSONEncoder
+
+
 _NAME = Field.for_types(
     u"name",
     [str],
@@ -61,6 +64,14 @@ def eliot_logged_test(f):
     class storage(object):
         pass
 
+
+    # On Python 3, we want to use our custom JSON encoder when validating
+    # messages can be encoded to JSON:
+    if PY3:
+        capture = lambda f : capture_logging(None, encoder_=BytesJSONEncoder)(f)
+    else:
+        capture = lambda f : capture_logging(None)(f)
+
     @wraps(f)
     def run_and_republish(self, *a, **kw):
         # Unfortunately the only way to get at the global/default logger...
@@ -85,7 +96,7 @@ def eliot_logged_test(f):
             # can finish the test's action.
             storage.action.finish()
 
-        @capture_logging(None)
+        @capture
         def run(self, logger):
             # Record the MemoryLogger for later message extraction.
             storage.logger = logger
@@ -165,9 +176,6 @@ class EliotLoggedRunTest(object):
 
     @eliot_logged_test
     def run(self, result=None):
-        # Workaround for https://github.com/itamarst/eliot/issues/456
-        if PY3:
-            self.case.eliot_logger._validate_message = lambda *args, **kwargs: None
         return self._run_tests_with_factory(
             self.case,
             self.handlers,