Dear all, If one specifies, say, "PKG_CXXFLAGS= -O3" in a Makevars file, it will not make a difference to how the code is compiled if -O2 is specified in $R_HOME/etc/Makeconf. This is because PKG_CXXFLAGS is prepended to the corresponding flags in $R_HOME/etc/Makeconf instead of being appended and gcc only uses the last optimisation flag specified. As a result, one has to use targets in Makevars, which adds unnecessary complication to the whole process. Would it be possible to ensure PKG_CXXFLAGS & co. are appended instead of prepended to the default flags and, if not, is there an easier workaround than specifying targets? (targets are easy enough under unix, but seems a bit more complicated under windows...) Thanks! E