Richard, > I used CPPFLAGS='-Df2cFortran -D_XOPEN_SOURCE=500' LDFLAGS='-lm' CC='gcc' > LIBS=-lm before of ./configure Replace LDFLAGS and LIBS with "LD_MATH=-lm" and try again. Execute the command "make distclean" before executing the "configure" script. Regards, Steve Emmerson Ticket Details =================== Ticket ID: FNG-611066 Department: Support UDUNITS Priority: Normal Status: Closed