Index: trunk/Mars/cmake/rootlogon.C.in
===================================================================
--- trunk/Mars/cmake/rootlogon.C.in	(revision 19326)
+++ trunk/Mars/cmake/rootlogon.C.in	(revision 19352)
@@ -44,5 +44,5 @@
 #include <iomanip>
 
-#if ROOT_VERSION_CODE != ROOT_VERSION(${ROOT_VERSION_MAJOR},${ROOT_VERSION_MINOR},${ROOT_VERSION_PATCH})
+#if defined(ROOT_VERSION_CODE) && (ROOT_VERSION_CODE != ROOT_VERSION(${ROOT_VERSION_MAJOR},${ROOT_VERSION_MINOR},${ROOT_VERSION_PATCH}))
 #error Started ROOT version does not match ROOT version linked with libmars.so
 #endif