diff --git a/doc/reference/algorithms/touches.qbk b/doc/reference/algorithms/touches.qbk
index b99c1bb6b..56e502c93 100644
--- a/doc/reference/algorithms/touches.qbk
+++ b/doc/reference/algorithms/touches.qbk
@@ -15,4 +15,5 @@
 [heading_conformance_ogc __this_function__..Touches]
 [? __one_parameter__ The version with one parameter is additional and not described in the OGC standard]
 
+[note only implemented for polygon/multi_polygon]