Index: trunk/Mars/CMakeLists.txt
===================================================================
--- trunk/Mars/CMakeLists.txt	(revision 19326)
+++ trunk/Mars/CMakeLists.txt	(revision 19327)
@@ -107,8 +107,18 @@
 # --------- ROOT -------------
 
+IF(NOT DEFINED ENV{ROOTSYS})
+   MESSAGE(FATAL_ERROR "ROOTSYS not defined. Please call 'source [root]/bin/thisroot.sh'")
+ENDIF()
+
 # You need to tell CMake where to find the ROOT installation. This can be done in a number of ways:
 #   - ROOT built with classic configure/make use the provided $ROOTSYS/etc/cmake/FindROOT.cmake
 #   - ROOT built with CMake. Add in CMAKE_PREFIX_PATH the installation prefix for ROOT
-SET(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "$ENV{ROOTSYS}/etc/cmake")
+IF(EXISTS $ENV{ROOTSYS}/ROOTConfig.cmake)
+   IF(NOT DEFINED ENV{CMAKE_PREFIX_PATH})
+      LIST(APPEND CMAKE_PREFIX_PATH $ENV{ROOTSYS})
+   ENDIF()
+ELSE()
+   SET(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "$ENV{ROOTSYS}/etc/cmake")
+ENDIF()
 
 #---Locate the ROOT package and defines a number of variables (e.g. ROOT_INCLUDE_DIRS)