diff --git a/flap/src/hopix/hopixParser.mly b/flap/src/hopix/hopixParser.mly
index 88a5908..2b66710 100644
--- a/flap/src/hopix/hopixParser.mly
+++ b/flap/src/hopix/hopixParser.mly
@@ -405,7 +405,7 @@ expression:
   }
 /* Allocation
  * ref expr */
-| REF e=located(mid_expression) {
+| REF e=located(simple_expression) {
     Ref(e)
   }
 /* Field record */