diff --git a/ml-agents/mlagents/trainers/stats.py b/ml-agents/mlagents/trainers/stats.py
index fe6ca6a924..2eec1993c7 100644
--- a/ml-agents/mlagents/trainers/stats.py
+++ b/ml-agents/mlagents/trainers/stats.py
@@ -13,6 +13,10 @@ class StatsSummary(NamedTuple):
     std: float
     num: int
 
+    @staticmethod
+    def empty() -> "StatsSummary":
+        return StatsSummary(0.0, 0.0, 0)
+
 
 class StatsWriter(abc.ABC):
     """
@@ -184,8 +188,10 @@ def get_stats_summaries(self, key: str) -> StatsSummary:
         :param key: The type of statistic, e.g. Environment/Reward.
         :returns: A StatsSummary NamedTuple containing (mean, std, count).
         """
-        return StatsSummary(
-            mean=np.mean(StatsReporter.stats_dict[self.category][key]),
-            std=np.std(StatsReporter.stats_dict[self.category][key]),
-            num=len(StatsReporter.stats_dict[self.category][key]),
-        )
+        if len(StatsReporter.stats_dict[self.category][key]) > 0:
+            return StatsSummary(
+                mean=np.mean(StatsReporter.stats_dict[self.category][key]),
+                std=np.std(StatsReporter.stats_dict[self.category][key]),
+                num=len(StatsReporter.stats_dict[self.category][key]),
+            )
+        return StatsSummary.empty()