diff --git a/fuzz/emulated/array/src/Main.ml b/fuzz/emulated/array/src/Main.ml
index be702e822dedbefd30510da5cb9865f60825a51b..e1f748f16793892fde648b423cd3d205931a5726 100644
--- a/fuzz/emulated/array/src/Main.ml
+++ b/fuzz/emulated/array/src/Main.ml
@@ -100,7 +100,7 @@ let predicate =
 (* Declare the abstract type [t] of arrays. *)
 
 let t =
-  declare_abstract_type "t" ~var:"a"
+  declare_abstract_type ~var:"a" ()
     (* We do not provide a [check] function. *)
 
 (* -------------------------------------------------------------------------- *)
diff --git a/fuzz/emulated/queue/src/Main.ml b/fuzz/emulated/queue/src/Main.ml
index 238b231f4b641b739a2007347d1d1804e361d05d..a63d63e10da6416719796dad73d07712fa121e57 100644
--- a/fuzz/emulated/queue/src/Main.ml
+++ b/fuzz/emulated/queue/src/Main.ml
@@ -57,7 +57,7 @@ let list_of_seq spec =
 (* Declare the abstract type [t] of queues. *)
 
 let t =
-  declare_abstract_type "t" ~var:"q"
+  declare_abstract_type ~var:"q" ()
     (* We do not provide a [check] function. *)
 
 (* -------------------------------------------------------------------------- *)
diff --git a/fuzz/emulated/stack/src/Main.ml b/fuzz/emulated/stack/src/Main.ml
index 17b9baa0fcd6d2f5604796c35712347db832b06b..7662cd599a285ad6badf18c7051fc4029009d3f2 100644
--- a/fuzz/emulated/stack/src/Main.ml
+++ b/fuzz/emulated/stack/src/Main.ml
@@ -57,7 +57,7 @@ let list_of_seq spec =
 (* Declare the abstract type [t] of stacks. *)
 
 let t =
-  declare_abstract_type "t" ~var:"s"
+  declare_abstract_type ~var:"s" ()
     (* We do not provide a [check] function. *)
 
 (* -------------------------------------------------------------------------- *)