diff --git a/services/mongodbflex/client.go b/services/mongodbflex/client.go
index 52fd62575..f3d429bf9 100644
--- a/services/mongodbflex/client.go
+++ b/services/mongodbflex/client.go
@@ -308,7 +308,7 @@ func (c *APIClient) prepareRequest(
 	var body *bytes.Buffer
 
 	// Detect postBody type and post.
-	if postBody != nil {
+	if !IsNil(postBody) {
 		contentType := headerParams["Content-Type"]
 		if contentType == "" {
 			contentType = detectContentType(postBody)