diff --git a/.ci/r_tests_windows.ps1 b/.ci/r_tests_windows.ps1
index 5af9413f..1c67c174 100644
--- a/.ci/r_tests_windows.ps1
+++ b/.ci/r_tests_windows.ps1
@@ -31,7 +31,7 @@ $env:_R_CHECK_EXAMPLE_TIMING_THRESHOLD_ = 30
 # see: https://stackoverflow.com/a/63837547/8302386
 $env:_R_CHECK_SYSTEM_CLOCK_ = 0
 
-$R_VER = "4.1.0"
+$R_VER = "4.1.1"
 $ProgressPreference = "SilentlyContinue"  # progress bar bug extremely slows down download speed
 Invoke-WebRequest -Uri https://cloud.r-project.org/bin/windows/base/old/$R_VER/R-$R_VER-win.exe -OutFile R-win.exe -MaximumRetryCount 5
 Start-Process -FilePath R-win.exe -NoNewWindow -Wait -ArgumentList "/VERYSILENT /DIR=$env:R_LIB_PATH\R /COMPONENTS=main,x64" ; Check-Output $?
@@ -50,6 +50,7 @@ Invoke-WebRequest -Uri https://sourceforge.net/projects/qpdf/files/qpdf/10.3.1/q
 Copy-Item .\qpdf -Destination $env:R_LIB_PATH -Recurse
 
 initexmf --set-config-value [MPM]AutoInstall=1
+$env:MIKTEX_EXCEPTION_PATH = "$env:TEMP\miktex"
 
 cd "$env:GITHUB_WORKSPACE\R-package"
 Add-Content .Renviron "R_LIBS=$env:R_LIB_PATH"
diff --git a/R-package/tests/testthat/setup.R b/R-package/tests/testthat/setup.R
index 04794efc..076938e3 100644
--- a/R-package/tests/testthat/setup.R
+++ b/R-package/tests/testthat/setup.R
@@ -41,3 +41,10 @@ y_MULTIclass = sample(1:5, 100, replace = TRUE)
 
 set.seed(6)
 W = runif(100)
+
+# Temporary I/O structures
+
+# default directory where the temporary 'rgf' files are saved
+#------------------------------------------------------------
+
+default_dir = file.path(dirname(tempdir()), 'rgf')
diff --git a/R-package/tests/testthat/teardown.R b/R-package/tests/testthat/teardown.R
new file mode 100644
index 00000000..f4398ff5
--- /dev/null
+++ b/R-package/tests/testthat/teardown.R
@@ -0,0 +1,4 @@
+context("teardown")
+
+# remove temporary 'rgf' files
+if (dir.exists(default_dir)) unlink(default_dir, recursive = TRUE, force = TRUE)
diff --git a/R-package/tests/testthat/test-RGF_package.R b/R-package/tests/testthat/test-RGF_package.R
index 0b10f7e1..d6c7b706 100644
--- a/R-package/tests/testthat/test-RGF_package.R
+++ b/R-package/tests/testthat/test-RGF_package.R
@@ -466,11 +466,6 @@ testthat::test_that("the 'cleanup' method (ESTIMATOR specific) works as expected
   skip_test_if_no_python()
   skip_test_if_no_module("rgf.sklearn")
 
-  #--------------------------------------------------------------------------------
-  # default directory where the temporary 'rgf' files are saved
-
-  default_dir = file.path(dirname(tempdir()), 'rgf')
-
   #--------------------------------------------------------------------------------
   # RGF
 
@@ -515,11 +510,6 @@ testthat::test_that("the 'cleanup' method (APPLIES TO ALL ESTIMATORS) works as e
   skip_test_if_no_python()
   skip_test_if_no_module("rgf.sklearn")
 
-  #--------------------------------------------------------------------------------
-  # default directory where the temporary 'rgf' files are saved
-
-  default_dir = file.path(dirname(tempdir()), 'rgf')
-
   #--------------------------------------------------------------------------------
   # RGF
 
@@ -549,4 +539,3 @@ testthat::test_that("the 'cleanup' method (APPLIES TO ALL ESTIMATORS) works as e
   testthat::expect_true( init_exists_upd_rgf && (init_num_files_rgf > 0) && (init_num_files_fastrgf > init_num_files_rgf) &&
                             ( init_num_files_rgf > length(lst_files_tmp) && init_num_files_fastrgf > length(lst_files_tmp_end_state) ) )       # normally, both initial and end state must have the same length [ length(lst_files_tmp) == length(lst_files_tmp_end_state) ]
 })
-