diff -rupN --no-dereference gmsh-4.6.0-source/CMakeLists.txt gmsh-4.6.0-source-new/CMakeLists.txt
--- gmsh-4.6.0-source/CMakeLists.txt	2020-06-23 09:36:33.018201852 +0200
+++ gmsh-4.6.0-source-new/CMakeLists.txt	2020-06-23 09:36:33.020201841 +0200
@@ -257,7 +257,7 @@ if(ENABLE_RPATH)
   # when building, don't use the install RPATH already (but later on when
   # installing)
   set(CMAKE_BUILD_WITH_INSTALL_RPATH FALSE)
-  set(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_PREFIX}/lib")
+  set(CMAKE_INSTALL_RPATH "${CMAKE_INSTALL_LIBDIR}")
 
   # add the automatically determined parts of the RPATH which point to
   # directories outside the build tree to the install RPATH