diff --git a/Eigen/src/SparseCore/SparseBlock.h b/Eigen/src/SparseCore/SparseBlock.h
index 13e8b0bf1..acaf933f4 100644
--- a/Eigen/src/SparseCore/SparseBlock.h
+++ b/Eigen/src/SparseCore/SparseBlock.h
@@ -130,7 +130,7 @@ public:
 
       // 2 - let's check whether there is enough allocated memory
       Index nnz           = tmp.nonZeros();
-      Index start         = m_outerStart==0 ? 0 : matrix.outerIndexPtr()[m_outerStart]; // starting position of the current block
+      Index start         = m_outerStart==0 ? 0 : m_matrix.outerIndexPtr()[m_outerStart]; // starting position of the current block
       Index end           = m_matrix.outerIndexPtr()[m_outerStart+m_outerSize.value()]; // ending position of the current block
       Index block_size    = end - start;                                                // available room in the current block
       Index tail_size     = m_matrix.outerIndexPtr()[m_matrix.outerSize()] - end;
@@ -139,6 +139,8 @@ public:
                           ? Index(matrix.data().allocatedSize()) + block_size
                           : block_size;
 
+      Index tmp_start = tmp.outerIndexPtr()[0];
+
       bool update_trailing_pointers = false;
       if(nnz>free_size) 
       {
@@ -148,8 +150,8 @@ public:
         internal::smart_copy(m_matrix.valuePtr(),       m_matrix.valuePtr() + start,      newdata.valuePtr());
         internal::smart_copy(m_matrix.innerIndexPtr(),  m_matrix.innerIndexPtr() + start, newdata.indexPtr());
 
-        internal::smart_copy(tmp.valuePtr(),      tmp.valuePtr() + nnz,       newdata.valuePtr() + start);
-        internal::smart_copy(tmp.innerIndexPtr(), tmp.innerIndexPtr() + nnz,  newdata.indexPtr() + start);
+        internal::smart_copy(tmp.valuePtr() + tmp_start,      tmp.valuePtr() + tmp_start + nnz,       newdata.valuePtr() + start);
+        internal::smart_copy(tmp.innerIndexPtr() + tmp_start, tmp.innerIndexPtr() + tmp_start + nnz,  newdata.indexPtr() + start);
 
         internal::smart_copy(matrix.valuePtr()+end,       matrix.valuePtr()+end + tail_size,      newdata.valuePtr()+start+nnz);
         internal::smart_copy(matrix.innerIndexPtr()+end,  matrix.innerIndexPtr()+end + tail_size, newdata.indexPtr()+start+nnz);
@@ -173,8 +175,8 @@ public:
           update_trailing_pointers = true;
         }
 
-        internal::smart_copy(tmp.valuePtr(),      tmp.valuePtr() + nnz,       matrix.valuePtr() + start);
-        internal::smart_copy(tmp.innerIndexPtr(), tmp.innerIndexPtr() + nnz,  matrix.innerIndexPtr() + start);
+        internal::smart_copy(tmp.valuePtr() + tmp_start,      tmp.valuePtr() + tmp_start + nnz,       matrix.valuePtr() + start);
+        internal::smart_copy(tmp.innerIndexPtr() + tmp_start, tmp.innerIndexPtr() + tmp_start + nnz,  matrix.innerIndexPtr() + start);
       }
 
       // update outer index pointers and innerNonZeros
diff --git a/test/sparse_block.cpp b/test/sparse_block.cpp
index 49a5f135e..cb5213ade 100644
--- a/test/sparse_block.cpp
+++ b/test/sparse_block.cpp
@@ -223,6 +223,33 @@ template<typename SparseMatrixType> void sparse_block(const SparseMatrixType& re
 
     VERIFY_IS_APPROX(m2.block(r0,c0,r1,c1), refMat2.block(r0,c0,r1,c1));
     VERIFY_IS_APPROX((2*m2).block(r0,c0,r1,c1), (2*refMat2).block(r0,c0,r1,c1));
+
+    if(m2.nonZeros()>0)
+    {
+      VERIFY_IS_APPROX(m2, refMat2);
+      SparseMatrixType m3(rows, cols);
+      DenseMatrix refMat3(rows, cols); refMat3.setZero();
+      Index n = internal::random<Index>(1,10);
+      for(Index k=0; k<n; ++k)
+      {
+        Index o1 = internal::random<Index>(0,outer-1);
+        Index o2 = internal::random<Index>(0,outer-1);
+        if(SparseMatrixType::IsRowMajor)
+        {
+          m3.innerVector(o1) = m2.row(o2);
+          refMat3.row(o1) = refMat2.row(o2);
+        }
+        else
+        {
+          m3.innerVector(o1) = m2.col(o2);
+          refMat3.col(o1) = refMat2.col(o2);
+        }
+        if(internal::random<bool>())
+          m3.makeCompressed();
+      }
+      if(m3.nonZeros()>0)
+      VERIFY_IS_APPROX(m3, refMat3);
+    }
   }
 }