diff --git a/lint.go b/lint.go
index df9a802..2899b29 100644
--- a/lint.go
+++ b/lint.go
@@ -1276,7 +1276,8 @@
 			if exportedType(typ) {
 				continue
 			}
-			f.errorf(ret.Type, 0.8, "exported %s %s returns unexported type %s, which can be annoying to use",
+			f.errorf(ret.Type, 0.8, category("unexported-type-in-api"),
+				"exported %s %s returns unexported type %s, which can be annoying to use",
 				thing, fn.Name.Name, typ)
 			break // only flag one
 		}