--- VTK/Filters/OpenTURNS/CMakeLists.txt.orig	2023-09-22 14:35:37 UTC
+++ VTK/Filters/OpenTURNS/CMakeLists.txt
@@ -1,6 +1,9 @@ find_package(OpenTURNS 1.8 REQUIRED)
 find_package(OpenTURNS 1.8 REQUIRED)
-# XXX(fixme)
-include(${OPENTURNS_USE_FILE})
+
+if (EXISTS "${OPENTURNS_USE_FILE}")
+  # removed in 1.21
+  include (${OPENTURNS_USE_FILE})
+endif ()
 
 set(classes
   vtkOTDensityMap
