diff --git a/GPy/mappings/__init__.py b/GPy/mappings/__init__.py
index 5193a232..39568c9f 100644
--- a/GPy/mappings/__init__.py
+++ b/GPy/mappings/__init__.py
@@ -6,4 +6,5 @@ from .linear import Linear
 from .mlp import MLP
 from .additive import Additive
 from .compound import Compound
+from .constant import Constant