diff --git a/subcmds/upload.py b/subcmds/upload.py
index f9c5e7f..8d949be 100644
--- a/subcmds/upload.py
+++ b/subcmds/upload.py
@@ -657,7 +657,7 @@
 
                 branch.uploaded = True
             except UploadError as e:
-                self.git_event_log.ErrorEvent("upload error: " + str(e))
+                self.git_event_log.ErrorEvent(f"upload error: {e}")
                 branch.error = e
                 branch.uploaded = False
                 have_errors = True