diff --git a/ci/benchmark/build.sh b/ci/benchmark/build.sh
index 979db1b5034..59bd908d151 100755
--- a/ci/benchmark/build.sh
+++ b/ci/benchmark/build.sh
@@ -98,7 +98,7 @@ conda list --show-channel-urls
 ################################################################################
 
 logger "Build libcudf..."
-if [[ ${BUILD_MODE} == "pull-request" ]]; then
+if [[ "${BUILD_MODE}" == "pull-request" ]]; then
     "$WORKSPACE/build.sh" clean libcudf cudf dask_cudf benchmarks tests --ptds
 else
     "$WORKSPACE/build.sh" clean libcudf cudf dask_cudf benchmarks tests -l --ptds
diff --git a/ci/cpu/upload.sh b/ci/cpu/upload.sh
index 40e80def8ae..e6ef72d930c 100755
--- a/ci/cpu/upload.sh
+++ b/ci/cpu/upload.sh
@@ -12,7 +12,7 @@ export GPUCI_RETRY_SLEEP=30
 export LABEL_OPTION=${LABEL_OPTION:-"--label main"}
 
 # Skip uploads unless BUILD_MODE == "branch"
-if [ ${BUILD_MODE} != "branch" ]; then
+if [ "${BUILD_MODE}" != "branch" ]; then
   echo "Skipping upload"
   return 0
 fi
diff --git a/ci/gpu/build.sh b/ci/gpu/build.sh
index 059e359e4e9..a8afc03af94 100755
--- a/ci/gpu/build.sh
+++ b/ci/gpu/build.sh
@@ -124,7 +124,7 @@ if [[ -z "$PROJECT_FLASH" || "$PROJECT_FLASH" == "0" ]]; then
     ################################################################################
 
     gpuci_logger "Build from source"
-    if [[ ${BUILD_MODE} == "pull-request" ]]; then
+    if [[ "${BUILD_MODE}" == "pull-request" ]]; then
         "$WORKSPACE/build.sh" clean libcudf cudf dask_cudf libcudf_kafka cudf_kafka benchmarks tests --ptds
     else
         "$WORKSPACE/build.sh" clean libcudf cudf dask_cudf libcudf_kafka cudf_kafka benchmarks tests -l --ptds
@@ -222,7 +222,7 @@ else
     install_dask
 
     gpuci_logger "Build python libs from source"
-    if [[ ${BUILD_MODE} == "pull-request" ]]; then
+    if [[ "${BUILD_MODE}" == "pull-request" ]]; then
         "$WORKSPACE/build.sh" cudf dask_cudf cudf_kafka --ptds
     else
         "$WORKSPACE/build.sh" cudf dask_cudf cudf_kafka -l --ptds