diff --git a/RbcUkqcd.hpp b/RbcUkqcd.hpp
index 840d1ee..5439b7b 100644
--- a/RbcUkqcd.hpp
+++ b/RbcUkqcd.hpp
@@ -123,7 +123,7 @@ struct RbcUkqcd
                                       const std::string boundary, const double residual);
   static inline void addC0StrangeSolver(Application &app, const std::string solverName,
                                         const std::string gaugeName,
-                                        const std::string boundary = "1 1 1 1",
+                                        const std::string boundary = "1 1 1 -1",
                                         const double residual = 1.0e-8);
   static inline void addM0StrangeSolver(Application &app, const std::string solverName,
                                         const std::string gaugeName,
@@ -149,7 +149,7 @@ struct RbcUkqcd
   // Charm solvers, mass is a free parameter
   static inline void addC0CharmSolver(Application &app, const std::string solverName,
                                       const std::string gaugeName, const double mass,
-                                      const std::string boundary = "1 1 1 1",
+                                      const std::string boundary = "1 1 1 -1",
                                       const double residual = 1.0e-18);
   static inline void addM0CharmSolver(Application &app, const std::string solverName,
                                       const std::string gaugeName, const double mass,