diff --git a/Eigen/Core b/Eigen/Core
index 63b9850c9..d45e45636 100644
--- a/Eigen/Core
+++ b/Eigen/Core
@@ -84,8 +84,8 @@
 #include <cmath>
 #include <cassert>
 #include <functional>
-#include <sstream>
 #ifndef EIGEN_NO_IO
+  #include <sstream>
   #include <iosfwd>
 #endif
 #include <cstring>
diff --git a/Eigen/src/Core/arch/Default/Half.h b/Eigen/src/Core/arch/Default/Half.h
index 7f9e6c12a..dfcfb657d 100644
--- a/Eigen/src/Core/arch/Default/Half.h
+++ b/Eigen/src/Core/arch/Default/Half.h
@@ -37,7 +37,6 @@
 #define EIGEN_HALF_H
 
 #include "../../InternalHeaderCheck.h"
-#include <sstream>
 
 #if defined(EIGEN_HAS_GPU_FP16) || defined(EIGEN_HAS_ARM64_FP16_SCALAR_ARITHMETIC)
 // When compiling with GPU support, the "__half_raw" base class as well as
diff --git a/Eigen/src/SparseCore/SparseMatrix.h b/Eigen/src/SparseCore/SparseMatrix.h
index 5e0c178c5..907855219 100644
--- a/Eigen/src/SparseCore/SparseMatrix.h
+++ b/Eigen/src/SparseCore/SparseMatrix.h
@@ -786,6 +786,7 @@ class SparseMatrix
     template<typename OtherDerived>
     EIGEN_DONT_INLINE SparseMatrix& operator=(const SparseMatrixBase<OtherDerived>& other);
 
+#ifndef EIGEN_NO_IO
     friend std::ostream & operator << (std::ostream & s, const SparseMatrix& m)
     {
       EIGEN_DBG_SPARSE(
@@ -830,6 +831,7 @@ class SparseMatrix
       s << static_cast<const SparseMatrixBase<SparseMatrix>&>(m);
       return s;
     }
+#endif
 
     /** Destructor */
     inline ~SparseMatrix()
diff --git a/Eigen/src/SparseCore/SparseMatrixBase.h b/Eigen/src/SparseCore/SparseMatrixBase.h
index 366588809..dc78c2eeb 100644
--- a/Eigen/src/SparseCore/SparseMatrixBase.h
+++ b/Eigen/src/SparseCore/SparseMatrixBase.h
@@ -214,7 +214,7 @@ template<typename Derived> class SparseMatrixBase
     inline void assignGeneric(const OtherDerived& other);
 
   public:
-
+#ifndef EIGEN_NO_IO
     friend std::ostream & operator << (std::ostream & s, const SparseMatrixBase& m)
     {
       typedef typename Derived::Nested Nested;
@@ -263,6 +263,7 @@ template<typename Derived> class SparseMatrixBase
       }
       return s;
     }
+#endif
 
     template<typename OtherDerived>
     Derived& operator+=(const SparseMatrixBase<OtherDerived>& other);
diff --git a/Eigen/src/SparseCore/SparseVector.h b/Eigen/src/SparseCore/SparseVector.h
index 7d7034f8d..ebbadb5c2 100644
--- a/Eigen/src/SparseCore/SparseVector.h
+++ b/Eigen/src/SparseCore/SparseVector.h
@@ -353,6 +353,7 @@ class SparseVector
     }
     #endif
 
+#ifndef EIGEN_NO_IO
     friend std::ostream & operator << (std::ostream & s, const SparseVector& m)
     {
       for (Index i=0; i<m.nonZeros(); ++i)
@@ -360,6 +361,7 @@ class SparseVector
       s << std::endl;
       return s;
     }
+#endif
 
     /** Destructor */
     inline ~SparseVector() {}
diff --git a/Eigen/src/SparseLU/SparseLU.h b/Eigen/src/SparseLU/SparseLU.h
index a0ca79a5b..9fd7e259d 100644
--- a/Eigen/src/SparseLU/SparseLU.h
+++ b/Eigen/src/SparseLU/SparseLU.h
@@ -754,10 +754,13 @@ void SparseLU<MatrixType, OrderingType>::factorize(const MatrixType& matrix)
       info = Base::pivotL(jj, m_diagpivotthresh, m_perm_r.indices(), iperm_c.indices(), pivrow, m_glu);
       if ( info ) 
       {
-        m_lastError = "THE MATRIX IS STRUCTURALLY SINGULAR ... ZERO COLUMN AT ";
+        m_lastError = "THE MATRIX IS STRUCTURALLY SINGULAR";
+#ifndef EIGEN_NO_IO
         std::ostringstream returnInfo;
-        returnInfo << info; 
+        returnInfo << " ... ZERO COLUMN AT ";
+        returnInfo << info;
         m_lastError += returnInfo.str();
+#endif
         m_info = NumericalIssue; 
         m_factorizationIsOk = false; 
         return;