Index: /trunk/Mars/CMakeLists.txt
===================================================================
--- /trunk/Mars/CMakeLists.txt	(revision 19345)
+++ /trunk/Mars/CMakeLists.txt	(revision 19346)
@@ -107,6 +107,6 @@
 # --------- ROOT -------------
 
-IF(NOT DEFINED ENV{ROOTSYS})
-   MESSAGE(FATAL_ERROR "ROOTSYS not defined. Please call 'source [root]/bin/thisroot.sh'")
+IF(NOT EXISTS root-config})
+   MESSAGE(WARNING "`root-config` not found in path. First make sure it is accessible.")
 ENDIF()