diff --git a/http/error.go b/http/error.go
index 90fac3206..1a3f07c04 100644
--- a/http/error.go
+++ b/http/error.go
@@ -17,7 +17,7 @@ package http
 // Error defines a standard application error.
 type Error struct {
 	// Machine-readable error code.
-	Code string `json:"code,omitempty"`
+	code string `json:"code,omitempty"`
 
 	// Human-readable message.
 	Message string `json:"message"`