diff --git a/git_config.py b/git_config.py
index 05b3c1ee..87ed9765 100644
--- a/git_config.py
+++ b/git_config.py
@@ -792,7 +792,7 @@ class SyncAnalysisState:
         """
         self._config = config
         now = datetime.datetime.utcnow()
-        self._Set("main.synctime", now.isoformat() + "Z")
+        self._Set("main.synctime", now.isoformat(timespec="microseconds") + "Z")
         self._Set("main.version", "1")
         self._Set("sys.argv", sys.argv)
         for key, value in superproject_logging_data.items():