diff --git a/tests/drivers/string.sh b/tests/drivers/string.sh
index 749f7adc..00397e1a 100644
--- a/tests/drivers/string.sh
+++ b/tests/drivers/string.sh
@@ -23,7 +23,11 @@ generate_random_string() {
   range=$(($2 - $1 + 1))
   size=$(($1 + RANDOM % range))
 
-  string=$(LC_ALL=C tr -dc 'A-Za-z0-9' < /dev/urandom | head -c "$size")
+  string=$({ LC_ALL=C tr -dc 'A-Za-z0-9' < /dev/urandom || true; } | head -c "$size")
+  if [ "${#string}" -eq 0 ]; then
+    log 2 "error generating string"
+    return 1
+  fi
   echo "$string"
   return 0
 }
diff --git a/tests/test_user_aws.sh b/tests/test_user_aws.sh
index 685d656e..a5ce2fd7 100755
--- a/tests/test_user_aws.sh
+++ b/tests/test_user_aws.sh
@@ -20,6 +20,7 @@ load ./bats-assert/load
 source ./tests/test_user_common.sh
 source ./tests/commands/get_object.sh
 source ./tests/commands/put_object.sh
+source ./tests/drivers/list_buckets/list_buckets.sh
 source ./tests/drivers/list_buckets/list_buckets_s3api.sh
 source ./tests/drivers/put_bucket_ownership_controls/put_bucket_ownership_controls_rest.sh
 source ./tests/drivers/file.sh
diff --git a/tests/test_user_s3cmd.sh b/tests/test_user_s3cmd.sh
index 9328729c..45257d8f 100755
--- a/tests/test_user_s3cmd.sh
+++ b/tests/test_user_s3cmd.sh
@@ -18,6 +18,7 @@ load ./bats-support/load
 load ./bats-assert/load
 
 source ./tests/drivers/list_buckets/list_buckets.sh
+source ./tests/drivers/list_buckets/list_buckets_s3api.sh
 source ./tests/drivers/put_bucket_ownership_controls/put_bucket_ownership_controls_rest.sh
 source ./tests/drivers/user.sh
 source ./tests/test_user_common.sh