diff --git a/lib/helpers/toFormData.js b/lib/helpers/toFormData.js
index a41e966..ec47d8c 100644
--- a/lib/helpers/toFormData.js
+++ b/lib/helpers/toFormData.js
@@ -120,6 +120,10 @@ function toFormData(obj, formData, options) {
       return value.toISOString();
     }
 
+    if (utils.isBoolean(value)) {
+      return value.toString();
+    }
+
     if (!useBlob && utils.isBlob(value)) {
       throw new AxiosError('Blob is not supported. Use a Buffer instead.');
     }