diff --git a/RbcUkqcd.hpp b/RbcUkqcd.hpp
index e7040e5..840d1ee 100644
--- a/RbcUkqcd.hpp
+++ b/RbcUkqcd.hpp
@@ -84,7 +84,7 @@ struct RbcUkqcd
                                                 const std::string gaugeName,
                                                 const std::string gaugeTransform,
                                                 const std::string eigenpackPath,
-                                                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