diff --git a/parlai/core/metrics.py b/parlai/core/metrics.py
index ae4fab29dea..7c0bd50cab4 100644
--- a/parlai/core/metrics.py
+++ b/parlai/core/metrics.py
@@ -85,7 +85,8 @@ def _bleu(guess, answers):
     # works with strings, which is better suited for this module.
     return nltkbleu.sentence_bleu(
         [normalize_answer(a).split(" ") for a in answers],
-        normalize_answer(guess).split(" ")
+        normalize_answer(guess).split(" "),
+        smoothing_function=nltkbleu.SmoothingFunction(epsilon=1e-12).method1,
     )