diff --git a/stale_repos.py b/stale_repos.py
index 9386828..8a8b8ca 100755
--- a/stale_repos.py
+++ b/stale_repos.py
@@ -74,9 +74,18 @@ def is_repo_exempt(repo, exempt_repos, exempt_topics):
     if exempt_repos and any(repo.name == exempt_repo for exempt_repo in exempt_repos):
         print(f"{repo.html_url} is exempt from stale repo check")
         return True
-    if exempt_topics and any(topic in exempt_topics for topic in repo.topics().names):
-        print(f"{repo.html_url} is exempt from stale repo check")
-        return True
+    try:
+        if exempt_topics and any(
+            topic in exempt_topics for topic in repo.topics().names
+        ):
+            print(f"{repo.html_url} is exempt from stale repo check")
+            return True
+    except github3.exceptions.NotFoundError as error_code:
+        if error_code.code == 404:
+            print(
+                f"{repo.html_url} does not have topics enabled and may be a private temporary fork"
+            )
+
     return False
 
 
diff --git a/test_stale_repos.py b/test_stale_repos.py
index 33a10bd..d019e59 100644
--- a/test_stale_repos.py
+++ b/test_stale_repos.py
@@ -569,6 +569,25 @@ def test_not_exempt(self):
 
         self.assertFalse(result)
 
+    def test_not_found_error(self):
+        """
+        Test that a repo is not exempt if a NotFoundError is raised
+        which happens for private temporary forks.
+        """
+        repo = MagicMock(name="repo", spec=["name", "html_url", "topics"])
+        repo.name = "not_exempt_repo"
+        repo.topics.side_effect = github3.exceptions.NotFoundError(
+            resp=MagicMock(status_code=404)
+        )
+        exempt_repos = []
+        exempt_topics = ["exempt_topic"]
+
+        result = is_repo_exempt(
+            repo=repo, exempt_repos=exempt_repos, exempt_topics=exempt_topics
+        )
+
+        self.assertFalse(result)
+
 
 if __name__ == "__main__":
     unittest.main()