Hi, Using the latest R-devel under Windows, I've encountered the following problem when trying to install packages at the prompt: >R CMD INSTALL d:\inum_0.1-0.tar.gz * installing to library 'C:\Users\henwin\R\win-library\3.4' * installing *source* package 'inum' ... ** R ** preparing package for lazy loading ** help *** installing help indices ** building package indices ** testing if installed package can be loaded *** arch - i386 Error: '\U' used without hex digits in character string starting "'C:\U" Execution halted *** arch - x64 Error: '\U' used without hex digits in character string starting "'C:\U" Execution halted ERROR: loading failed for 'i386', 'x64' * removing 'C:\Users\henwin\R\win-library\3.4/inum' So, it seems that it doesn't correctly escape the '\' anymore...? However, installing from within Rgui works without a hitch. Also, in latest R-3.3.1patched it works as expected: C:\Program Files\R\R-3.3.1patched\bin>R CMD INSTALL d:\inum_0.1-0.tar.gz * installing to library 'C:/Users/hennil/R/win-library/3.3' * installing *source* package 'inum' ... ** R ** preparing package for lazy loading ** help *** installing help indices ** building package indices ** testing if installed package can be loaded *** arch - i386 *** arch - x64 * DONE (inum) Is this a known issue? Or is it just me...? Henric Winell