diff --git a/scripts/bash_completion_test.sh b/scripts/bash_completion_test.sh
index 82a0fa3..1f261bc 100755
--- a/scripts/bash_completion_test.sh
+++ b/scripts/bash_completion_test.sh
@@ -99,7 +99,7 @@
 # in STDERR receiving a string containing regex unexpected-error.
 assert_expansion_error_not_contains() {
   local prefix=$1 not_expected=$2 flags=${3:-}
-  local temp_file=$(mktemp -t tmp.stderr.XXXXXX)
+  local temp_file="$(mktemp "${TEST_TMPDIR}/tmp.stderr.XXXXXX")"
   for i in ${COMMAND_ALIASES[@]}; do
     local nprefix="$i "
     expand "$nprefix\t" "$flags" "$temp_file" > /dev/null