diff --git a/repo_cloner/lib/detector.py b/repo_cloner/lib/detector.py
index 034329e..8398e95 100644
--- a/repo_cloner/lib/detector.py
+++ b/repo_cloner/lib/detector.py
@@ -173,7 +173,11 @@ class Detector:
 	def run(self, callback: Callable[[DetectedCommit], None]) -> int:
 		log.info(f"Running commit detector")
 		new_branches = self._repo.list_branches()
+		if not new_branches:
+			new_branches = []
 		new_tags = self._repo.list_tags()
+		if not new_tags:
+			new_tags = []
 
 		# remove removed
 		old_keys = self._branches.keys()