diff --git a/readthedocs/core/adapters.py b/readthedocs/core/adapters.py
index 0a9daee022f..170f8954e26 100644
--- a/readthedocs/core/adapters.py
+++ b/readthedocs/core/adapters.py
@@ -1,7 +1,7 @@
 """Allauth overrides"""
 
 from __future__ import absolute_import
-import pickle
+import json
 import logging
 
 from allauth.account.adapter import DefaultAccountAdapter
@@ -32,12 +32,12 @@ def send_mail(self, template_prefix, email, context):
         subject = self.format_email_subject(subject)
 
         # Allauth sends some additional data in the context, remove it if the
-        # pieces can't be pickled
+        # pieces can't be json encoded
         removed_keys = []
         for key in list(context.keys()):
             try:
-                _ = pickle.dumps(context[key])  # noqa for F841
-            except (pickle.PickleError, TypeError):
+                _ = json.dumps(context[key])  # noqa for F841
+            except (ValueError, TypeError):
                 removed_keys.append(key)
                 del context[key]
         if removed_keys: