diff --git a/rest_framework/compat.py b/rest_framework/compat.py
index fffc17938..5a4bcdf66 100644
--- a/rest_framework/compat.py
+++ b/rest_framework/compat.py
@@ -161,6 +161,10 @@ def is_guardian_installed():
     """
     django-guardian is optional and only imported if in INSTALLED_APPS.
     """
+    if six.PY2:
+        # Guardian 1.5.0, for Django 2.2 is NOT compatible with Python 2.7.
+        # Remove when dropping PY2.
+        return False
     return 'guardian' in settings.INSTALLED_APPS