diff --git a/powerline/lib/vcs/__init__.py b/powerline/lib/vcs/__init__.py
index ea11b345..ba00eca2 100644
--- a/powerline/lib/vcs/__init__.py
+++ b/powerline/lib/vcs/__init__.py
@@ -196,7 +196,7 @@ class TreeStatusCache(dict):
 			if self.tw(key, ignore_event=getattr(repo, 'ignore_event', None)):
 				self.pop(key, None)
 		except OSError as e:
-			self.pl.warn('Failed to check %s for changes, with error: %s' % key, e)
+			self.pl.warn('Failed to check {0} for changes, with error: {1}', key, str(e))
 		return self.cache_and_get(key, repo.status)
 
 
diff --git a/powerline/segments/common.py b/powerline/segments/common.py
index ecb77700..8aefb16b 100644
--- a/powerline/segments/common.py
+++ b/powerline/segments/common.py
@@ -69,7 +69,11 @@ def branch(pl, segment_info, create_watcher, status_colors=False):
 		branch = repo.branch()
 		scol = ['branch']
 		if status_colors:
-			status = tree_status(repo, pl)
+			try:
+				status = tree_status(repo, pl)
+			except Exception as e:
+				pl.exception('Failed to compute tree status: {0}', str(e))
+				status = '?'
 			scol.insert(0, 'branch_dirty' if status and status.strip() else 'branch_clean')
 		return [{
 			'contents': branch,