 NMR/MetaPropagation.cc |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/NMR/MetaPropagation.cc b/NMR/MetaPropagation.cc
index b7ed98b..ce8c16f 100755
--- a/NMR/MetaPropagation.cc
+++ b/NMR/MetaPropagation.cc
@@ -2136,7 +2136,7 @@ SpinOpGenerator::add_A0(T& dest,F func, double coup, size_t j, size_t sk, Type2T
       { ref_.clear(0); }
     const space_T& operator()() const { return ref_; }
     ~fudge_isotropic_() { ref_.ensure_rank(0); }
-    mutable space_T& ref_;
+    space_T& ref_;
   };
   template<> struct fudge_isotropic_<double> { 
     fudge_isotropic_(double v) : v_(v) {};
