* checking for file ‘./DESCRIPTION’ ... OK
* preparing ‘mkin’:
* checking DESCRIPTION meta-information ... OK
* installing the package to build vignettes
* creating vignettes ... OK
* checking for LF line-endings in source and make files and shell scripts
* checking for empty or unneeded directories
* looking to see if a ‘data/datalist’ file should be added
  NB: this package now depends on R (>= 3.5.0)
  WARNING: Added dependency on R >= 3.5.0 because serialized objects in  serialize/load version 3 cannot be read in older versions of R.  File(s) containing such objects: 'mkin/vignettes/mkin_benchmarks.rda'
* building 'mkin_0.9.49.4.tar.gz'