diff --git a/language-server/lsp/proofState.ml b/language-server/lsp/proofState.ml
index a28e6054..9e4b3540 100644
--- a/language-server/lsp/proofState.ml
+++ b/language-server/lsp/proofState.ml
@@ -13,7 +13,7 @@
 (**************************************************************************)
 type hyp = {
   identifiers: string list;
-  type_ : string;
+  type_ : string; [@key "type"]
   diff: string;
   body: string option; [@yojson.option]
 } [@@deriving yojson]