diff --git a/src/superagent.js b/src/superagent.js
index e6a11408a..a8d3b2dfb 100644
--- a/src/superagent.js
+++ b/src/superagent.js
@@ -33,8 +33,9 @@ class Request {
         this.okFunc = ({ status }) => status >=200 && status <= 299;
         this.timer = { timeout: 0, id: null, controller: null };
         this.retryCount = 0;
-        this.body = null;
+        this.body = Buffer.alloc(0);
         this.redirectCount = 5;
+        this.boundary = null; // multipart only
     }
 
     async _handleResponse(url, response) {
@@ -82,7 +83,7 @@ class Request {
                 if (error) reject(error); else resolve(result);
             });
 
-            if (this.body) request.write(this.body);
+            request.write(this.body);
 
             request.end();
         });
@@ -170,15 +171,29 @@ class Request {
         return this;
     }
 
+    field(name, value) {
+        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}"\r\n\r\n`, 'utf8');
+        const partData = Buffer.from(value, 'utf8');
+        const partTrailer = Buffer.from(`\r\n--${this.boundary}--\r\n`, 'utf8');
+        this.body = Buffer.concat([this.body, partHeader, partData, partTrailer]);
+
+        this.options.headers['content-type'] = `multipart/form-data; boundary=${this.boundary}`;
+        this.options.headers['content-length'] = this.body.byteLength;
+
+        return this;
+    }
+
     attach(name, filepath) { // this is only used in tests and thus simplistic
-        const boundary = '----WebKitFormBoundary' + Math.random().toString(36).substring(2);
+        if (!this.boundary) this._boundary = '----WebKitFormBoundary' + Math.random().toString(36).substring(2);
 
-        const partHeader = Buffer.from(`--${boundary}\r\nContent-Disposition: form-data; name="${name}" filename="${path.basename(filepath)}"\r\n\r\n`, 'utf8');
+        const partHeader = Buffer.from(`--${this.boundary}\r\nContent-Disposition: form-data; name="${name}" filename="${path.basename(filepath)}"\r\n\r\n`, 'utf8');
         const partData = fs.readFileSync(filepath);
-        const partTrailer = Buffer.from(`\r\n--${boundary}--\r\n`, 'utf8');
-        this.body = Buffer.concat([partHeader, partData, partTrailer]);
+        const partTrailer = Buffer.from(`\r\n--${this.boundary}--\r\n`, 'utf8');
+        this.body = Buffer.concat([this.body, partHeader, partData, partTrailer]);
 
-        this.options.headers['content-type'] = `multipart/form-data; boundary=${boundary}`;
+        this.options.headers['content-type'] = `multipart/form-data; boundary=${this.boundary}`;
         this.options.headers['content-length'] = this.body.byteLength;
 
         return this;