diff --git a/ConvDO/boundaries.py b/ConvDO/boundaries.py
index 34444b5..7596687 100644
--- a/ConvDO/boundaries.py
+++ b/ConvDO/boundaries.py
@@ -55,7 +55,7 @@ def __add__(self, other):
         else:
             try:
                 # Dirichlet+number=Dirichlet
-                return DirichletBoundary(self.boundary_value*other)
+                return DirichletBoundary(self.boundary_value+other)
             except TypeError:
                 return NotImplemented