diff --git a/lib/private/Files/ObjectStore/S3ConnectionTrait.php b/lib/private/Files/ObjectStore/S3ConnectionTrait.php
index 9405c2cf33492..f676ece2ddaad 100644
--- a/lib/private/Files/ObjectStore/S3ConnectionTrait.php
+++ b/lib/private/Files/ObjectStore/S3ConnectionTrait.php
@@ -105,11 +105,11 @@ public function getBucket() {
 	 * @return array with encryption parameters
 	 */
 	public function getSseKmsPutParameters(): array {
-		if (isset($this->sseKmsBucketKeyId)) {
+		if (empty($this->sseKmsBucketKeyId)) {
 			return [
 				'ServerSideEncryption' => 'aws:kms',
 			];
-		} elseif (isset($this->sseKmsKeyId)) {
+		} elseif (empty($this->sseKmsKeyId)) {
 			return [
 				'ServerSideEncryption' => 'aws:kms',
 				'SSEKMSKeyId' => $this->sseKmsKeyId,
@@ -127,12 +127,12 @@ public function getSseKmsPutParameters(): array {
 	 * @return array with encryption parameters
 	 */
 	public function getSseKmsGetParameters(): array {
-		if (isset($this->sseKmsBucketKeyId)) {
+		if (empty($this->sseKmsBucketKeyId)) {
 			return [
 				'ServerSideEncryption' => 'aws:kms',
 				'SSEKMSKeyId' => $this->sseKmsBucketKeyId,
 			];
-		} elseif (isset($this->sseKmsKeyId)) {
+		} elseif (empty($this->sseKmsKeyId)) {
 			return [
 				'ServerSideEncryption' => 'aws:kms',
 				'SSEKMSKeyId' => $this->sseKmsKeyId,