diff --git a/src/polyfill/Fetch.js b/src/polyfill/Fetch.js
index 77ec06cd3..8015b313b 100644
--- a/src/polyfill/Fetch.js
+++ b/src/polyfill/Fetch.js
@@ -47,7 +47,7 @@ class RNFetchBlobFetchPolyfill {
         // When request body is a Blob, use file URI of the Blob as request body.
         else if (body.isRNFetchBlobPolyfill)
           promise = Promise.resolve(RNFetchBlob.wrap(body.blobPath))
-        else if (typeof body !== 'object')
+        else if (typeof body !== 'object' && options.headers['Content-Type'] !== 'application/json')
           promise = Promise.resolve(JSON.stringify(body))
         else if (typeof body !== 'string')
           promise = Promise.resolve(body.toString())