diff --git a/Eigen/src/Core/products/GeneralMatrixMatrix.h b/Eigen/src/Core/products/GeneralMatrixMatrix.h
index 2ab773e64..7bb26c1ab 100644
--- a/Eigen/src/Core/products/GeneralMatrixMatrix.h
+++ b/Eigen/src/Core/products/GeneralMatrixMatrix.h
@@ -245,7 +245,7 @@ struct ei_gemm_functor
   protected:
     const Lhs& m_lhs;
     const Rhs& m_rhs;
-    mutable Dest& m_dest;
+    Dest& m_dest;
     Scalar m_actualAlpha;
 };