diff --git a/triqs/mc_tools/mc_move_set.hpp b/triqs/mc_tools/mc_move_set.hpp
index 43178a7b..fcfb7967 100644
--- a/triqs/mc_tools/mc_move_set.hpp
+++ b/triqs/mc_tools/mc_move_set.hpp
@@ -183,16 +183,22 @@ namespace triqs { namespace mc_tools {
     std::cerr <<"  Proposition probability = "<<proba<<std::endl;
 #endif
     MCSignType rate_ratio = current->attempt();
-    if (!std::isfinite(std::abs(rate_ratio)))
-     TRIQS_RUNTIME_ERROR<<"Monte Carlo Error : the rate is not finite in move "<<name_of_currently_selected();
-    double abs_rate_ratio = std::abs(rate_ratio);
+    double abs_rate_ratio;
+    if (std::isinf(rate_ratio)) { // in case the ratio is infinite
+     abs_rate_ratio = 100; //1.e30; // >1 for metropolis
+     try_sign_ratio = (std::signbit(rate_ratio) ? -1 : 1); // signbit -> true iif the number is negative
+    } else {
+     if (!std::isfinite(std::abs(rate_ratio)))
+      TRIQS_RUNTIME_ERROR << "Monte Carlo Error : the rate is not finite in move " << name_of_currently_selected();
+     abs_rate_ratio = std::abs(rate_ratio);
 #ifdef TRIQS_TOOLS_MC_DEBUG
-    std::cerr << " Metropolis ratio " << rate_ratio<<". Abs(Metropolis ratio) " <<abs_rate_ratio << std::endl;
+     std::cerr << " Metropolis ratio " << rate_ratio << ". Abs(Metropolis ratio) " << abs_rate_ratio << std::endl;
 #endif
-    assert ((abs_rate_ratio>=0));
-    try_sign_ratio = ( abs_rate_ratio> 1.e-14 ? rate_ratio/abs_rate_ratio : 1); // keep the sign
-    return abs_rate_ratio;
+    assert((abs_rate_ratio >= 0));
+    try_sign_ratio = (abs_rate_ratio > 1.e-14 ? rate_ratio / abs_rate_ratio : 1); // keep the sign
    }
+   return abs_rate_ratio;
+  }
 
    /**
     *  accept the move previously selected and tried.