diff --git a/Code/Learning/otbConfusionMatrixCalculator.txx b/Code/Learning/otbConfusionMatrixCalculator.txx
index 648b9d84a1b941e67572b27ecfe78062bac92520..0f8cb8d21949161c049830a7ea3bea50dae28a0e 100644
--- a/Code/Learning/otbConfusionMatrixCalculator.txx
+++ b/Code/Learning/otbConfusionMatrixCalculator.txx
@@ -83,6 +83,7 @@ ConfusionMatrixCalculator<TRefListLabel,TProdListLabel>
   m_NumberOfClasses = countClasses;
 
   m_ConfusionMatrix = ConfusionMatrixType(m_NumberOfClasses, m_NumberOfClasses);
+  m_ConfusionMatrix.Fill(0);
 
   refIterator = m_ReferenceLabels->Begin();
   prodIterator = m_ProducedLabels->Begin();