diff --git a/apps/readest-app/src/utils/misc.ts b/apps/readest-app/src/utils/misc.ts
index df604fc4..c4de55d6 100644
--- a/apps/readest-app/src/utils/misc.ts
+++ b/apps/readest-app/src/utils/misc.ts
@@ -9,7 +9,7 @@ export const getContentMd5 = (content: unknown) => md5(JSON.stringify(content));
 
 export const makeSafeFilename = (filename: string, replacement = '_') => {
   // Windows restricted characters + control characters and reserved names
-  const unsafeCharacters = /[<>:"\/\\|?*\x00-\x1F]/g;
+  const unsafeCharacters = /[<>:%"\/\\|?*\x00-\x1F]/g;
   const reservedFilenames = /^(con|prn|aux|nul|com[1-9]|lpt[1-9])$/i;
   // Unsafe to use filename including file extensions over 255 bytes on Android
   const maxFilenameBytes = 250;