diff --git a/application/Config/Mimes.php b/application/Config/Mimes.php
index bcb232181d92..cd7f2b3e85f4 100644
--- a/application/Config/Mimes.php
+++ b/application/Config/Mimes.php
@@ -313,7 +313,7 @@ public static function guessExtensionFromType(string $type, ?string $proposed_ex
 
 		$proposed_extension = trim(strtolower($proposed_extension));
 
-		if(!is_null($proposed_extension) && array_key_exists($proposed_extension, self::$mimes) && in_array($type, self::$mimes[$proposed_extension]))
+		if(!is_null($proposed_extension) && array_key_exists($proposed_extension, self::$mimes) && in_array($type, is_string(self::$mimes[$proposed_extension])?[self::$mimes[$proposed_extension]]:self::$mimes[$proposed_extension]))
 		{
 			return $proposed_extension;
 		}