diff --git a/lib/Controller/ApiController.php b/lib/Controller/ApiController.php
index 2f534839..7b03e4b0 100644
--- a/lib/Controller/ApiController.php
+++ b/lib/Controller/ApiController.php
@@ -53,11 +53,13 @@
 use OCP\Share\IShare;
 use Psr\Log\LoggerInterface;
 
-function str_to_stream(string $string) {
-	$stream = fopen('php://memory', 'r+');
-	fwrite($stream, $string);
-	rewind($stream);
-	return $stream;
+if (!function_exists(__NAMESPACE__ . '\str_to_stream')) {
+	function str_to_stream(string $string) {
+		$stream = fopen('php://memory', 'r+');
+		fwrite($stream, $string);
+		rewind($stream);
+		return $stream;
+	}
 }
 
 class ApiController extends OCSController {
diff --git a/lib/Controller/DownloadController.php b/lib/Controller/DownloadController.php
index 9e0cc575..f8936572 100644
--- a/lib/Controller/DownloadController.php
+++ b/lib/Controller/DownloadController.php
@@ -39,11 +39,13 @@
 use OCP\IURLGenerator;
 use OCP\IUserSession;
 
-function str_to_stream(string $string) {
-	$stream = fopen('php://memory', 'r+');
-	fwrite($stream, $string);
-	rewind($stream);
-	return $stream;
+if (!function_exists(__NAMESPACE__ . '\str_to_stream')) {
+	function str_to_stream(string $string) {
+		$stream = fopen('php://memory', 'r+');
+		fwrite($stream, $string);
+		rewind($stream);
+		return $stream;
+	}
 }
 
 class DownloadController extends Controller {