diff --git a/src/main/scala/gitbucket/core/controller/ControllerBase.scala b/src/main/scala/gitbucket/core/controller/ControllerBase.scala
index 63949ab..7d261b2 100644
--- a/src/main/scala/gitbucket/core/controller/ControllerBase.scala
+++ b/src/main/scala/gitbucket/core/controller/ControllerBase.scala
@@ -30,6 +30,10 @@
 
   implicit val jsonFormats = DefaultFormats
 
+  before("/api/v3/*") {
+    contentType = formats("json")
+  }
+
 // TODO Scala 2.11
 //  // Don't set content type via Accept header.
 //  override def format(implicit request: HttpServletRequest) = ""