diff --git a/com.oracle.truffle.r.test.cran/r/install.cran.packages.R b/com.oracle.truffle.r.test.cran/r/install.cran.packages.R
index 4c3f8f1105920af20a86e7f48488153f62c10bb7..8cf210cda483b9f05b0f9b09d7fab2fce9463c86 100644
--- a/com.oracle.truffle.r.test.cran/r/install.cran.packages.R
+++ b/com.oracle.truffle.r.test.cran/r/install.cran.packages.R
@@ -611,7 +611,7 @@ install.pkg <- function(pkgname) {
 system.install <- function(pkgname) {
 	script <- normalizePath("com.oracle.truffle.r.test.cran/r/install.package.R")
 	if (is.fastr()) {
-		rscript = normalizePath("bin/Rscript")
+		rscript = file.path(R.home(), "bin", "Rscript")
 	} else {
 		rscript = "Rscript"
 	}
@@ -655,7 +655,7 @@ is.fastr <- function() {
 system.test <- function(pkgname) {
 	script <- normalizePath("com.oracle.truffle.r.test.cran/r/test.package.R")
 	if (is.fastr()) {
-		rscript = normalizePath("bin/Rscript")
+		rscript = file.path(R.home(), "bin", "Rscript")
 	} else {
 		rscript = "Rscript"
 	}