diff --git a/capnp/lib/capnp.pyx b/capnp/lib/capnp.pyx
index afbb3bf..e824b2e 100644
--- a/capnp/lib/capnp.pyx
+++ b/capnp/lib/capnp.pyx
@@ -2199,7 +2199,7 @@ cdef class _DynamicCapabilityClient:
             return self._cached_schema
 
     def __dir__(self):
-        return list(set(self.schema.method_names_inherited) + tuple(dir(self.__class__)))
+        return list(set(self.schema.method_names_inherited + tuple(dir(self.__class__))))
 
 
 cdef class _CapabilityClient: