diff --git a/configure.ac b/configure.ac
index e590b29b..244ffebb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -421,7 +421,7 @@ dnl -----------------------------------------------
 dnl Check for ROOT
 dnl -----------------------------------------------
 
-ROOT_PATH([5.22/00], [], AC_MSG_ERROR([Either ROOT is not installed correctly or the version is too old... please check!]))
+ROOT_PATH([6.06/00], [], AC_MSG_ERROR([Either ROOT is not installed correctly or the version is too old... please check!]))
 
 ROOT_LIBS="-L${ROOTLIBDIR} ${ROOTGLIBS} ${ROOTAUXLIBS} -lMinuit2 -lMathMore -lXMLParser"
 ROOT_CFLAGS="-I${ROOTINCDIR} ${ROOTCFLAGS} ${ROOTAUXCFLAGS}"