diff --git a/src/index.js b/src/index.js
index f4c86f2..050d8fb 100644
--- a/src/index.js
+++ b/src/index.js
@@ -142,11 +142,14 @@ export default (function create(defaults) {
 				}
 			}
 		}
-		
+
 		const fetchFunc = options.fetch || fetch;
 		const customHeaders = {};
 
-		if (data && typeof data === 'object') {
+		if (data && data instanceof FormData) {
+			customHeaders['Content-Type'] = 'application/x-www-form-urlencoded';
+		}
+		else if (data && typeof data === 'object') {
 			data = JSON.stringify(data);
 			customHeaders['Content-Type'] = 'application/json';
 		}
diff --git a/test/index.test.js b/test/index.test.js
index 8327ba5..d050c60 100644
--- a/test/index.test.js
+++ b/test/index.test.js
@@ -83,4 +83,25 @@ describe('redaxios', () => {
 		expect(res.status).toEqual(200);
 		expect(JSON.parse(res.data)).toEqual({ hello: 'world' });
 	});
+
+	it('should send formData as application/x-www-form-urlencoded', async() => {
+		const oldFetch = window.fetch;
+		try {
+			window.fetch = jasmine.createSpy('fetch').and.returnValue(Promise.resolve({ ok: true, status: 200, text: () => Promise.resolve('yep') }));
+			const data = new FormData();
+			data.append('hello', 'world');
+			axios.post('/foo', data);
+			expect(window.fetch).toHaveBeenCalledTimes(1);
+			expect(window.fetch).toHaveBeenCalledWith('/foo', jasmine.objectContaining({
+				method: 'post',
+				headers: {
+					'content-type': 'application/x-www-form-urlencoded'
+				},
+				body: data
+			}));
+		}
+		finally {
+			window.fetch = oldFetch;
+		}
+	});
 });