diff --git a/lib/private/Log/LogDetails.php b/lib/private/Log/LogDetails.php
index c82904d7cea40..2e37ec1bb2f1f 100644
--- a/lib/private/Log/LogDetails.php
+++ b/lib/private/Log/LogDetails.php
@@ -108,7 +108,7 @@ public function logDetailsAsJSON(string $app, $message, int $level): string {
 			if (is_string($value)) {
 				$testEncode = json_encode($value, JSON_UNESCAPED_SLASHES);
 				if ($testEncode === false) {
-					$entry[$key] = utf8_encode($value);
+					$entry[$key] = mb_convert_encoding($value, 'UTF-8', mb_detect_encoding($value));
 				}
 			}
 		}