diff --git a/Eigen/src/IterativeLinearSolvers/ConjugateGradient.h b/Eigen/src/IterativeLinearSolvers/ConjugateGradient.h
index 10cd94783..fab5fdb1f 100644
--- a/Eigen/src/IterativeLinearSolvers/ConjugateGradient.h
+++ b/Eigen/src/IterativeLinearSolvers/ConjugateGradient.h
@@ -208,7 +208,7 @@ public:
   template<typename Rhs,typename Dest>
   void _solve_impl(const MatrixBase<Rhs>& b, Dest& x) const
   {
-    x.setOnes();
+    x.setZero();
     _solve_with_guess_impl(b.derived(),x);
   }