Index: Eigen/src/SparseCore/SparseMatrix.h
===================================================================
--- Eigen/src/SparseCore/SparseMatrix.h	(revision 321)
+++ Eigen/src/SparseCore/SparseMatrix.h	(working copy)
@@ -1027,6 +1027,10 @@
 class SparseMatrix<Scalar,_Options,_Index>::InnerIterator
 {
   public:
+    InnerIterator()
+      : m_values(0), m_indices(0), m_outer(0), m_id(0), m_end(0)
+    { }
+
     InnerIterator(const SparseMatrix& mat, Index outer)
       : m_values(mat.valuePtr()), m_indices(mat.innerIndexPtr()), m_outer(outer), m_id(mat.m_outerIndex[outer])
     {
@@ -1051,7 +1055,7 @@
   protected:
     const Scalar* m_values;
     const Index* m_indices;
-    const Index m_outer;
+    Index m_outer;
     Index m_id;
     Index m_end;
 };