diff --git a/headroom/proxy/prometheus_metrics.py b/headroom/proxy/prometheus_metrics.py
index 889ed60be..fe477290b 100644
--- a/headroom/proxy/prometheus_metrics.py
+++ b/headroom/proxy/prometheus_metrics.py
@@ -417,14 +417,14 @@ class PrometheusMetrics:
             return total_input_tokens, total_input_cost_usd
 
         try:
-            # totals() rather than stats(): identical numbers, without the
-            # 31-day cost-record walk that stats()["budget_basis"] performs and
-            # this caller throws away. See CostTracker.totals.
-            tracked_input_tokens, tracked_input_cost_usd = self.cost_tracker.totals()
+            cost_stats = self.cost_tracker.stats()
         except Exception:
             logger.debug("Failed to read cost tracker totals for savings history", exc_info=True)
             return total_input_tokens, total_input_cost_usd
 
+        tracked_input_tokens = cost_stats.get("total_input_tokens")
+        tracked_input_cost_usd = cost_stats.get("total_input_cost_usd")
+
         if tracked_input_tokens is not None:
             try:
                 total_input_tokens = self._savings_tracker_input_tokens_offset + max(