diff --git a/src/superagent.js b/src/superagent.js
index a6b6af39a..a3f0d5ccc 100644
--- a/src/superagent.js
+++ b/src/superagent.js
@@ -190,11 +190,12 @@ class Request {
         return this;
     }
 
-    attach(name, filepath) { // this is only used in tests and thus simplistic
+    attach(name, filepathOrBuffer) { // this is only used in tests and thus simplistic
         if (!this.#boundary) this.#boundary = '----WebKitFormBoundary' + Math.random().toString(36).substring(2);
 
-        const partHeader = Buffer.from(`--${this.#boundary}\r\nContent-Disposition: form-data; name="${name}" filename="${path.basename(filepath)}"\r\n\r\n`, 'utf8');
-        const partData = fs.readFileSync(filepath);
+        const filename = Buffer.isBuffer(filepathOrBuffer) ? name : path.basename(filepathOrBuffer);
+        const partHeader = Buffer.from(`--${this.#boundary}\r\nContent-Disposition: form-data; name="${name}" filename="${filename}"\r\n\r\n`, 'utf8');
+        const partData = Buffer.isBuffer(filepathOrBuffer) ? filepathOrBuffer : fs.readFileSync(filepathOrBuffer);
         this.#body = Buffer.concat([this.#body, partHeader, partData, Buffer.from('\r\n', 'utf8')]);
 
         return this;