diff -ruN coin/src/doc/CMakeLists.txt my/src/doc/CMakeLists.txt
--- coin/src/doc/CMakeLists.txt	2019-12-23 20:47:44.000000000 +0100
+++ my/src/doc/CMakeLists.txt	2022-10-17 21:02:17.868469249 +0200
@@ -30,7 +30,8 @@
     endif()
   endif()
   if(COIN_BUILD_DOCUMENTATION_QTHELP)
-    find_program(QHG_LOCATION NAMES qhelpgenerator qhelpgenerator-qt5 DOC "Qt qhelpgenerator")
+    find_package(Qt5Help REQUIRED)
+    get_target_property(QHG_LOCATION Qt5::qhelpgenerator LOCATION)
     if(NOT QHG_LOCATION)
       message(FATAL_ERROR "Missing program Qt qhelpgenerator")
     else()