diff --git a/docs/conf.py b/docs/conf.py
index d16a0f2..974706f 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -40,7 +40,7 @@ master_doc = 'index'
 
 # General information about the project.
 project = 'django-mailbox'
-copyright = '2014, Adam Coddington'
+copyright = '2020, Adam Coddington'
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
@@ -282,7 +282,7 @@ def process_docstring(app, what, name, obj, options, lines):
 
             # Add the field's type to the docstring
             if isinstance(field, models.ForeignKey):
-                to = field.rel.to
+                to = field.related_model
                 lines.append(':type {}: {} to :class:`~{}.{}`'.format(field.attname, type(field).__name__, to.__module__, to.__name__))
             else:
                 lines.append(':type {}: {}'.format(field.attname, type(field).__name__))
diff --git a/tox.ini b/tox.ini
index fcbd986..6998106 100644
--- a/tox.ini
+++ b/tox.ini
@@ -26,6 +26,7 @@ commands=
 deps=
     sphinx
     -r{toxinidir}/rtd_requirements.txt
+    .
 commands=make html clean SPHINXOPTS="-W --keep-going"
 changedir={toxinidir}/docs
 allowlist_externals=make