diff --git a/icefall/diagnostics.py b/icefall/diagnostics.py
index c808f15d4..036016a46 100644
--- a/icefall/diagnostics.py
+++ b/icefall/diagnostics.py
@@ -401,7 +401,7 @@ class ScalarDiagnostic(object):
         sum_gradsq = self.sum_gradsq.to(device='cpu', dtype=torch.float32)
         sum_abs_grad = self.sum_abs_grad.to(device='cpu', dtype=torch.float32)
 
-        counts_cumsum = self.counts.cumsum(dim=0)
+        counts_cumsum = counts.cumsum(dim=0)
         counts_tot = counts_cumsum[-1]
 
         # subdivide the distribution up into `num_bins` intervals for analysis, for greater