diff --git a/pytorch_pretrained_bert/optimization.py b/pytorch_pretrained_bert/optimization.py
index df5b50b51d..ca973015a6 100644
--- a/pytorch_pretrained_bert/optimization.py
+++ b/pytorch_pretrained_bert/optimization.py
@@ -54,7 +54,7 @@ class LRSchedule(object):
         """
         if self.t_total < 0:
             return 1.
-        progress = step / self.t_total
+        progress = float(step) / self.t_total
         ret = self.get_lr_(progress)
         # warning for exceeding t_total (only active with warmup_linear
         if not nowarn and self.warn_t_total and progress > 1. and progress > self.warned_for_t_total_at_progress: