diff --git a/hb.elpi b/hb.elpi
index 9b62b2714..fa7b46d7e 100644
--- a/hb.elpi
+++ b/hb.elpi
@@ -2028,7 +2028,7 @@ main-declare-structure Module GRFSwP ClosureCheck :- std.do! [
   ElpiOperationModName is "ElpiOperations" ^ {std.any->string {new_int}},
   coq.env.begin-module ElpiOperationModName none,
     std.map MLToExport (m\r\ r = mixin-first-class m ClassName) MixinFirstClass,
-    std.forall {std.append EX MixinFirstClass} (c\ acc current (clause _ _ c)),
+    std.forall {std.append EX MixinFirstClass} (c\ hb-accumulate current (clause _ _ c)),
   coq.env.end-module ElpiOperations,
   export ElpiOperations,