diff --git a/doc/APIreference.rst b/doc/APIreference.rst
index f8cd48fa..9bfaa2e4 100644
--- a/doc/APIreference.rst
+++ b/doc/APIreference.rst
@@ -6579,6 +6579,8 @@ mju_sigmoid
 
 Sigmoid function over 0<=x<=1 constructed from half-quadratics.
 
+.. _mjd_transitionFD:
+
 mjd_transitionFD
 ~~~~~~~~~~~~~~~~