--- a/configure.ac
+++ b/configure.ac
@@ -134,8 +134,8 @@
  ;;
 esac
 
-CFLAGS="$CCFLAGS64 $CPPCMNTFLAGS $OPTIMFLAGS $DEBUGFLAGS $WARNFLAGS"
-AC_MSG_RESULT([$CFLAGS])
+AM_CFLAGS="$CCFLAGS64 $CPPCMNTFLAGS $OPTIMFLAGS $DEBUGFLAGS $WARNFLAGS"
+AC_MSG_RESULT([$AM_CFLAGS])
 AC_SUBST([OBJECT_MODE])
 
 AS_IF([test "x$enable_antlrdebug" = xno], [AC_DEFINE([ANTLR3_NODEBUGGER], [1], [Define if ANTLR debugger not required])], [])