Today, I needed to update the version of Rtools I use at work. But: the original installation was done by IT, in the default path of C:/Rtools; I don’t have write access there, and I didn’t want to wait for IT to do it for me. “I’ll just install it under my user folder. How hard can it be?”


The manual is a good place to start. The Rtools.txt file that comes with the installer is pretty clear about the requirements:

  1. Add Rtools\bin to your system PATH environment variable.
  2. Tell R where to find the compilers with BINPREF.

An example for setting the BINPREF environment variable is also given:


With an explanation:

Note how we embed another variable $(WIN) which is set by R to either “32” or “64” depending on the target. Thereby this BINPREF works for both architectures. Also note that R requires forward slashes here.

There’s two additional pieces of information I wish I had known:

  1. The path must not have spaces in it.
  2. The trailing forward slash must be there.


The BINPREF I was originally trying to use looked like this:

BINPREF="C:/Program Files/R/Rtools-3.5/mingw_$(WIN)/bin"

Running pkgbuild::has_compiler(debug = TRUE) gave me:

/usr/bin/sh: C:/Program: No such file or directory

Okay, no spaces allowed. I considered, for a moment, changing the installation directory again. Thankfully I realized that using a “short path name” would probably work. Conveniently, R includes a utility function to find one. For me:

shortPathName("C:/Program Files/R/Rtools-3.5")
#> [1] "C:\\PROGRA~1\\R\\Rtools-3.5"

With my updated BINPREF in hand, I was faced with a new error:

/usr/bin/sh: C:/PROGRA~1/R/Rtools-3.5/mingw_64/bingcc: No such file or directory

After a bit of staring, I noticed that the name of the compiler was just concatenated to the path witout a separator. It was trying to find a folder named bingcc rather than a file named gcc in the bin folder. Added the trailing forward slash to BINPREF, and it works.

#> Your system is ready to build packages!

Fantastic! 🎉


In summary: set the following in your .Renviron, making sure the path to your installation location is formatted such that it has no spaces. Be sure to have BINPREF end with a trailing forward slash.