diff --git a/built/index.js b/built/index.js
index 07a0fa7..a0a1305 100644
--- a/built/index.js
+++ b/built/index.js
@@ -217,6 +217,9 @@ function correctFilename(filename, ext) {
     if (ext === 'jpg' && filename.endsWith('.jpeg')) {
         return filename;
     }
+    if (ext === 'tif' && filename.endsWith('.tiff')) {
+        return filename;
+    }
     return `${filename}${dotExt}`;
 }
 function contentDisposition(type, filename) {
diff --git a/package.json b/package.json
index 80d8831..16fe28c 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "misskey-media-proxy",
-  "version": "0.0.15",
+  "version": "0.0.16",
   "description": "The Media Proxy for Misskey",
   "main": "built/index.js",
   "packageManager": "pnpm@7.26.0",
diff --git a/src/index.ts b/src/index.ts
index 314bfa1..2bb616e 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -273,6 +273,9 @@ function correctFilename(filename: string, ext: string | null) {
     if (ext === 'jpg' && filename.endsWith('.jpeg')) {
         return filename;
     }
+    if (ext === 'tif' && filename.endsWith('.tiff')) {
+        return filename;
+    }
     return `${filename}${dotExt}`;
 }