diff --git a/NEWS.md b/NEWS.md
index 8869d3a7..bbb64a54 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -5,7 +5,8 @@
 * Ensure system-wide installation of `cmake` in the list of suggestions to install it when missing.
 * Update GHA scripts to latest versions.
 * Configure git to always use LF line endings for configure.ac file.
-* Temporarily remove CI on windows devel.
+* Add CI for R-devel on Windows with Rtools42.
+* Fix for compatibility with versions of R anterior to `4.0` (#111).
 
 # nloptr 2.0.0
 
diff --git a/src/scripts/r_config.sh b/src/scripts/r_config.sh
index 158c0a0a..5f2118a9 100755
--- a/src/scripts/r_config.sh
+++ b/src/scripts/r_config.sh
@@ -34,8 +34,11 @@ if test -z "$CXX"; then
     echo >&2 "Could not detect C++ compiler with R CMD config."
 fi
 
-AR=`"${R_HOME}/bin${R_ARCH_BIN}/R" CMD config AR`
-AR=`which $AR`
+${R_HOME}/bin${R_ARCH_BIN}/Rscript --vanilla -e 'getRversion() > "4.0.0"' | grep TRUE > /dev/null
+if [ $? -eq 0 ]; then
+ 	AR=`"${R_HOME}/bin${R_ARCH_BIN}/R" CMD config AR`
+ 	AR=`which $AR`
 
-RANLIB=`"${R_HOME}/bin${R_ARCH_BIN}/R" CMD config RANLIB`
-RANLIB=`which $RANLIB`
+ 	RANLIB=`"${R_HOME}/bin${R_ARCH_BIN}/R" CMD config RANLIB`
+ 	RANLIB=`which $RANLIB`
+fi
diff --git a/tools/cmake_call.sh b/tools/cmake_call.sh
index 80e7245f..e19191cd 100755
--- a/tools/cmake_call.sh
+++ b/tools/cmake_call.sh
@@ -13,12 +13,18 @@ cd src
 sh ./scripts/nlopt_download.sh ${RSCRIPT_BIN}
 dot() { file=$1; shift; . "$file"; }
 dot ./scripts/r_config.sh ""
+${RSCRIPT_BIN} --vanilla -e 'getRversion() > "4.0.0"' | grep TRUE > /dev/null
+if [ $? -eq 0 ]; then
+  CMAKE_ADD_AR="-D CMAKE_AR=${AR}"
+  CMAKE_ADD_RANLIB="-D CMAKE_RANLIB=${RANLIB}"
+else
+ 	CMAKE_ADD_AR=""
+  CMAKE_ADD_RANLIB=""
+fi
 ${CMAKE_BIN} \
   -D BUILD_SHARED_LIBS=OFF \
   -D CMAKE_BUILD_TYPE=Release \
   -D INSTALL_LIB_DIR=nlopt/lib \
-  -D CMAKE_AR=${AR} \
-  -D CMAKE_RANLIB=${RANLIB} \
   -D NLOPT_CXX=ON \
   -D NLOPT_GUILE=OFF \
   -D NLOPT_MATLAB=OFF \
@@ -27,7 +33,7 @@ ${CMAKE_BIN} \
   -D NLOPT_SWIG=OFF \
   -D NLOPT_TESTS=OFF \
   -S nlopt-src \
-  -B nlopt-build
+  -B nlopt-build ${CMAKE_ADD_AR} ${CMAKE_ADD_RANLIB}
 sh ./scripts/nlopt_install.sh ${CMAKE_BIN} ${NCORES} ""
 
 # Cleanup