Do you mean this command: seal_diff_cpp.so: seal_diff_cpp.o $(CXX) -Wl,--no-undefined -shared -o seal_diff_cpp.so seal_diff_cpp.o $(LDFLAGS) If yes then the -lseal is added with the $(LDFLAGS) at the end of the command. -- Sent from: http://www.postgresql-archive.org/PostgreSQL-general-f1843780.html