diff --git a/Modules/Learning/LearningBase/include/otbImageClassificationFilter.hxx b/Modules/Learning/LearningBase/include/otbImageClassificationFilter.hxx
index 66b65aa8b0c2f22d20f0dd6afe68c2458468b940..4aea60a2dade1cfa0a281d19573e8a6084da0918 100644
--- a/Modules/Learning/LearningBase/include/otbImageClassificationFilter.hxx
+++ b/Modules/Learning/LearningBase/include/otbImageClassificationFilter.hxx
@@ -342,7 +342,7 @@ ImageClassificationFilter<TInputImage, TOutputImage, TMaskImage>
        {
          //The probas may have different size than the m_NumberOfClasses set by the user
          auto tempProbaValues = probas->GetMeasurementVector(labIt.GetInstanceIdentifier());
-         for(auto i=0; i<m_NumberOfClasses; ++i)
+         for(unsigned int i=0; i<m_NumberOfClasses; ++i)
          {
            if(i<tempProbaValues.Size()) probaValues[i] = tempProbaValues[i];
            else probaValues[i] = 0;