diff --git a/workflow.go b/workflow.go
index 1f4fb24..b08819f 100644
--- a/workflow.go
+++ b/workflow.go
@@ -194,11 +194,10 @@ func (wf *Workflow) SetBody(params ...interface{}) *Workflow {
 		if plen >= 2 {
 			t := params[plen-1]
 			defaultContentType = t.(string)
-			wf.Body.SetPrefix(defaultContentType)
-		} else {
-			wf.Body.SetPrefix(defaultContentType)
 		}
 
+		wf.Body.SetPrefix(defaultContentType)
+
 		if defaultContentType == TypeFormData {
 			createMultipart(wf.Body, params)
 		} else {