diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorConcatenation.h b/unsupported/Eigen/CXX11/src/Tensor/TensorConcatenation.h
index 78214df11..1a736ee2b 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorConcatenation.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorConcatenation.h
@@ -155,20 +155,20 @@ struct TensorEvaluator<const TensorConcatenationOp<Axis, LeftArgType, RightArgTy
       m_rightStrides[0] = 1;
       m_outputStrides[0] = 1;
 
-      for (int i = 1; i < NumDims; ++i) {
-        m_leftStrides[i] = m_leftStrides[i-1] * lhs_dims[i-1];
-        m_rightStrides[i] = m_rightStrides[i-1] * rhs_dims[i-1];
-        m_outputStrides[i] = m_outputStrides[i-1] * m_dimensions[i-1];
+      for (int j = 1; j < NumDims; ++j) {
+        m_leftStrides[j] = m_leftStrides[j-1] * lhs_dims[j-1];
+        m_rightStrides[j] = m_rightStrides[j-1] * rhs_dims[j-1];
+        m_outputStrides[j] = m_outputStrides[j-1] * m_dimensions[j-1];
       }
     } else {
       m_leftStrides[NumDims - 1] = 1;
       m_rightStrides[NumDims - 1] = 1;
       m_outputStrides[NumDims - 1] = 1;
 
-      for (int i = NumDims - 2; i >= 0; --i) {
-        m_leftStrides[i] = m_leftStrides[i+1] * lhs_dims[i+1];
-        m_rightStrides[i] = m_rightStrides[i+1] * rhs_dims[i+1];
-        m_outputStrides[i] = m_outputStrides[i+1] * m_dimensions[i+1];
+      for (int j = NumDims - 2; j >= 0; --j) {
+        m_leftStrides[j] = m_leftStrides[j+1] * lhs_dims[j+1];
+        m_rightStrides[j] = m_rightStrides[j+1] * rhs_dims[j+1];
+        m_outputStrides[j] = m_outputStrides[j+1] * m_dimensions[j+1];
       }
     }
   }
diff --git a/unsupported/Eigen/CXX11/src/Tensor/TensorImagePatch.h b/unsupported/Eigen/CXX11/src/Tensor/TensorImagePatch.h
index 59b70ad5c..a513f1891 100644
--- a/unsupported/Eigen/CXX11/src/Tensor/TensorImagePatch.h
+++ b/unsupported/Eigen/CXX11/src/Tensor/TensorImagePatch.h
@@ -142,15 +142,15 @@ struct TensorEvaluator<const TensorImagePatchOp<Rows, Cols, ArgType>, Device>
 
     switch (op.padding_type()) {
       case PADDING_VALID:
-        m_outputRows = ceil((m_inputRows - op.patch_rows() + 1.f) / static_cast<float>(m_row_strides));
-        m_outputCols = ceil((m_inputCols - op.patch_cols() + 1.f) / static_cast<float>(m_col_strides));
+        m_outputRows = std::ceil((m_inputRows - op.patch_rows() + 1.f) / static_cast<float>(m_row_strides));
+        m_outputCols = std::ceil((m_inputCols - op.patch_cols() + 1.f) / static_cast<float>(m_col_strides));
         // Calculate the padding
         m_rowPaddingTop = ((m_outputRows - 1) * m_row_strides + op.patch_rows() - m_inputRows) / 2;
         m_colPaddingLeft = ((m_outputCols - 1) * m_col_strides + op.patch_cols() - m_inputCols) / 2;
         break;
       case PADDING_SAME:
-        m_outputRows = ceil(m_inputRows / static_cast<float>(m_row_strides));
-        m_outputCols = ceil(m_inputCols / static_cast<float>(m_col_strides));
+        m_outputRows = std::ceil(m_inputRows / static_cast<float>(m_row_strides));
+        m_outputCols = std::ceil(m_inputCols / static_cast<float>(m_col_strides));
         // Calculate the padding
         m_rowPaddingTop = ((m_outputRows - 1) * m_row_strides + op.patch_rows() - m_inputRows) / 2;
         m_colPaddingLeft = ((m_outputCols - 1) * m_col_strides + op.patch_cols() - m_inputCols) / 2;