diff --git a/.circleci/unittest/linux/scripts/install.sh b/.circleci/unittest/linux/scripts/install.sh
index 966a6b45eb7..65273c75152 100755
--- a/.circleci/unittest/linux/scripts/install.sh
+++ b/.circleci/unittest/linux/scripts/install.sh
@@ -10,9 +10,15 @@ set -e
 eval "$(./conda/bin/conda shell.bash hook)"
 conda activate ./env
 
-if [ -z "${CUDA_VERSION:-}" ] ; then
+if [ "${CU_VERSION:-}" == cpu ] ; then
     cudatoolkit="cpuonly"
 else
+    if [[ ${#CU_VERSION} -eq 4 ]]; then
+        CUDA_VERSION="${CU_VERSION:2:1}.${CU_VERSION:3:1}"
+    elif [[ ${#CU_VERSION} -eq 5 ]]; then
+        CUDA_VERSION="${CU_VERSION:2:2}.${CU_VERSION:4:1}"
+    fi
+    echo "Using CUDA $CUDA_VERSION as determined by CU_VERSION"
     version="$(python -c "print('.'.join(\"${CUDA_VERSION}\".split('.')[:2]))")"
     cudatoolkit="cudatoolkit=${version}"
 fi
diff --git a/.circleci/unittest/windows/scripts/install.sh b/.circleci/unittest/windows/scripts/install.sh
index 584a868562d..b0f585a5483 100644
--- a/.circleci/unittest/windows/scripts/install.sh
+++ b/.circleci/unittest/windows/scripts/install.sh
@@ -12,9 +12,15 @@ this_dir="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
 eval "$(./conda/Scripts/conda.exe 'shell.bash' 'hook')"
 conda activate ./env
 
-if [ -z "${CUDA_VERSION:-}" ] ; then
+if [ "${CU_VERSION:-}" == cpu ] ; then
     cudatoolkit="cpuonly"
 else
+    if [[ ${#CU_VERSION} -eq 4 ]]; then
+        CUDA_VERSION="${CU_VERSION:2:1}.${CU_VERSION:3:1}"
+    elif [[ ${#CU_VERSION} -eq 5 ]]; then
+        CUDA_VERSION="${CU_VERSION:2:2}.${CU_VERSION:4:1}"
+    fi
+    echo "Using CUDA $CUDA_VERSION as determined by CU_VERSION"
     version="$(python -c "print('.'.join(\"${CUDA_VERSION}\".split('.')[:2]))")"
     cudatoolkit="cudatoolkit=${version}"
 fi