Index: trunk/Mars/CMakeLists.txt
===================================================================
--- trunk/Mars/CMakeLists.txt	(revision 19758)
+++ trunk/Mars/CMakeLists.txt	(revision 19759)
@@ -211,4 +211,14 @@
          -Wcast-align -Wformat -Woverloaded-virtual \
          -Wnon-virtual-dtor -Wshadow -fPIC") # -Wextra
+
+# /opt/root-6.18.04-bin/include/Bytes.h:72:6: warning: cast from 'char *' to 'UShort_t *'
+#       (aka 'unsigned short *') increases required alignment from 1 to 2 [-Wcast-align]
+#    *((UShort_t *)buf) = Rbswap_16(x);
+#      ^~~~~~~~~~~~~~~
+
+IF(ROOT_VERSION VERSION_GREATER_EQUAL 6.18 AND ROOT_VERSION VERSION_LESS 6.19)
+   SET(CMAKE_CXX_FLAGS
+       "${CMAKE_CXX_FLAGS} -Wno-cast-align")
+ENDIF()
 
 SET(CMAKE_CXX_FLAGS