diff --git a/cmake/Modules/OpmInit.cmake b/cmake/Modules/OpmInit.cmake
index bc2318800..76770ce91 100644
--- a/cmake/Modules/OpmInit.cmake
+++ b/cmake/Modules/OpmInit.cmake
@@ -110,8 +110,8 @@ macro (OpmInitDirVars)
   endif (COMMAND dir_hook)
 endmacro ()
 
-if("${CMAKE_SIZEOF_VOID_P}" STREQUAL "4")
-  message(FATAL_ERROR "OPM will only work correctly on 64bit systems!")
+if("${CMAKE_SIZEOF_VOID_P}" LESS 8)
+  message(FATAL_ERROR "OPM will only work correctly on 64bit (or higher) systems!")
 endif()
 
 OpmInitProjVars ()