diff --git a/src/proto_alpha/lib_protocol/sc_rollup_errors.ml b/src/proto_alpha/lib_protocol/sc_rollup_errors.ml
index 19e181bef9db331a6af48e71cb9b5ab6549ea56d..c4b932e3ef0af23311c87f3a95d6b3cb6b6755f5 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_errors.ml
+++ b/src/proto_alpha/lib_protocol/sc_rollup_errors.ml
@@ -56,6 +56,7 @@ type error +=
   | (* `Temporary *) Sc_rollup_invalid_outbox_message_index
   | (* `Temporary *) Sc_rollup_outbox_level_expired
   | (* `Temporary *) Sc_rollup_outbox_message_already_applied
+  | (* `Temporary *) Sc_rollup_state_change_on_zero_tick_commitment
   | (* `Temporary *)
       Sc_rollup_staker_funds_too_low of {
       staker : Signature.public_key_hash;
@@ -73,11 +74,13 @@ type error +=
       (Raw_level_repr.t * Raw_level_repr.t)
 
 let () =
+  let description = "Maximum number of available messages reached" in
   register_error_kind
     `Temporary
     ~id:"Sc_rollup_max_number_of_available_messages_reached"
     ~title:"Maximum number of available messages reached"
-    ~description:"Maximum number of available messages reached"
+    ~description
+    ~pp:(fun ppf () -> Format.fprintf ppf "%s" description)
     Data_encoding.unit
     (function
       | Sc_rollup_max_number_of_available_messages_reached -> Some ()
@@ -144,11 +147,13 @@ let () =
         ])
     (function Sc_rollup_staker_in_game x -> Some x | _ -> None)
     (fun x -> Sc_rollup_staker_in_game x) ;
+  let description = "Attempt to timeout game too early" in
   register_error_kind
     `Temporary
     ~id:"Sc_rollup_timeout_level_not_reached"
     ~title:"Attempt to timeout game too early"
-    ~description:"Attempt to timeout game too early"
+    ~description
+    ~pp:(fun ppf () -> Format.fprintf ppf "%s" description)
     Data_encoding.unit
     (function Sc_rollup_timeout_level_not_reached -> Some () | _ -> None)
     (fun () -> Sc_rollup_timeout_level_not_reached) ;
@@ -174,19 +179,25 @@ let () =
     Data_encoding.unit
     (function Sc_rollup_no_game -> Some () | _ -> None)
     (fun () -> Sc_rollup_no_game) ;
+  let description = "Attempt to play move but not staker's turn" in
   register_error_kind
     `Temporary
     ~id:"Sc_rollup_wrong_turn"
     ~title:"Attempt to play move but not staker's turn"
-    ~description:"Attempt to play move but not staker's turn"
+    ~description
+    ~pp:(fun ppf () -> Format.fprintf ppf "%s" description)
     Data_encoding.unit
     (function Sc_rollup_wrong_turn -> Some () | _ -> None)
     (fun () -> Sc_rollup_wrong_turn) ;
+  let description =
+    "Maximum number of messages reached for commitment period"
+  in
   register_error_kind
     `Temporary
     ~id:"Sc_rollup_max_number_of_messages_reached_for_commitment_period"
     ~title:"Maximum number of messages reached for commitment period"
-    ~description:"Maximum number of messages reached for commitment period"
+    ~description
+    ~pp:(fun ppf () -> Format.fprintf ppf "%s" description)
     Data_encoding.unit
     (function
       | Sc_rollup_max_number_of_messages_reached_for_commitment_period ->
@@ -376,6 +387,17 @@ let () =
     Data_encoding.empty
     (function Sc_rollup_outbox_message_already_applied -> Some () | _ -> None)
     (fun () -> Sc_rollup_outbox_message_already_applied) ;
+  let description = "Attempt to commit zero ticks with state change" in
+  register_error_kind
+    `Temporary
+    ~id:"Sc_rollup_state_change_on_zero_tick_commitment"
+    ~title:description
+    ~description
+    ~pp:(fun ppf () -> Format.fprintf ppf "%s" description)
+    Data_encoding.empty
+    (function
+      | Sc_rollup_state_change_on_zero_tick_commitment -> Some () | _ -> None)
+    (fun () -> Sc_rollup_state_change_on_zero_tick_commitment) ;
   register_error_kind
     `Temporary
     ~id:"Sc_rollup_staker_funds_too_low"
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_game_repr.ml b/src/proto_alpha/lib_protocol/sc_rollup_game_repr.ml
index 2d0c8abe41e1c337cba7356e6b8b443b35e99c63..982e4832e571d573c1941f51c3e0a4946de5fe5c 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_game_repr.ml
+++ b/src/proto_alpha/lib_protocol/sc_rollup_game_repr.ml
@@ -230,18 +230,25 @@ let initial inbox ~pvm_name ~(parent : Sc_rollup_commitment_repr.t)
     ~(child : Sc_rollup_commitment_repr.t) ~refuter ~defender =
   let ({alice; _} : Index.t) = Index.make refuter defender in
   let alice_to_play = Staker.equal alice refuter in
-  let tick = Sc_rollup_tick_repr.of_number_of_ticks child.number_of_ticks in
+  let open Sc_rollup_tick_repr in
+  let tick = of_number_of_ticks child.number_of_ticks in
   {
     turn = (if alice_to_play then Alice else Bob);
     inbox_snapshot = inbox;
     level = child.inbox_level;
     pvm_name;
     dissection =
-      [
-        make_chunk (Some parent.compressed_state) Sc_rollup_tick_repr.initial;
-        make_chunk (Some child.compressed_state) tick;
-        make_chunk None (Sc_rollup_tick_repr.next tick);
-      ];
+      (if equal tick initial then
+       [
+         make_chunk (Some child.compressed_state) initial;
+         make_chunk None (next initial);
+       ]
+      else
+        [
+          make_chunk (Some parent.compressed_state) initial;
+          make_chunk (Some child.compressed_state) tick;
+          make_chunk None (next tick);
+        ]);
   }
 
 type step =
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_game_repr.mli b/src/proto_alpha/lib_protocol/sc_rollup_game_repr.mli
index 3092e5f93b4eed708f5b748e35c07ac564029dbb..d5f73ed9c99fa43bf7eab9cfaa615fa6de0b8a61 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_game_repr.mli
+++ b/src/proto_alpha/lib_protocol/sc_rollup_game_repr.mli
@@ -162,7 +162,10 @@ module V1 : sig
 
     Invariants:
     -----------
-    - [dissection] must contain at least 3 values
+    - [dissection] must contain at least 2 values (normally it will be 32
+    values, but smaller if there isn't enough space for a dissection
+    that size. The initial game dissection will be 3 values except in
+    the case of a zero-tick commit when it will have 2 values.)
     - the first state hash value in [dissection] must not be [None]
     - [inbox_snapshot] never changes once the game is created
   *)
diff --git a/src/proto_alpha/lib_protocol/sc_rollup_stake_storage.ml b/src/proto_alpha/lib_protocol/sc_rollup_stake_storage.ml
index 54b3b33d0720afdc78ee109ec994d45c72e315e7..b7a25fcae81d1b6f9f3ce79b5904000c99de9b53 100644
--- a/src/proto_alpha/lib_protocol/sc_rollup_stake_storage.ml
+++ b/src/proto_alpha/lib_protocol/sc_rollup_stake_storage.ml
@@ -169,17 +169,36 @@ let assert_commitment_period ctxt rollup commitment =
   in
   return ctxt
 
+let assert_same_hash_as_predecessor ctxt rollup (commitment : Commitment.t) =
+  let open Lwt_tzresult_syntax in
+  let* pred, ctxt =
+    Commitment_storage.get_commitment_unsafe ctxt rollup commitment.predecessor
+  in
+  if
+    Sc_rollup_repr.State_hash.equal
+      pred.compressed_state
+      commitment.compressed_state
+  then return ctxt
+  else fail Sc_rollup_state_change_on_zero_tick_commitment
+
 (** Check invariants on [inbox_level], enforcing overallocation of storage and
     regularity of block production.
 
-     The constants used by [assert_refine_conditions_met] must be chosen such
-     that the maximum cost of storage allocated by each staker is at most the size
-     of their deposit.
+    The constants used by [assert_refine_conditions_met] must be chosen such
+    that the maximum cost of storage allocated by each staker is at most the size
+    of their deposit.
  *)
 let assert_refine_conditions_met ctxt rollup lcc commitment =
   let open Lwt_tzresult_syntax in
   let* ctxt = assert_commitment_not_too_far_ahead ctxt rollup lcc commitment in
-  assert_commitment_period ctxt rollup commitment
+  let* ctxt = assert_commitment_period ctxt rollup commitment in
+  if
+    Int32.equal
+      (Sc_rollup_repr.Number_of_ticks.to_int32
+         Commitment.(commitment.number_of_ticks))
+      0l
+  then assert_same_hash_as_predecessor ctxt rollup commitment
+  else return ctxt
 
 let get_commitment_stake_count ctxt rollup node =
   let open Lwt_tzresult_syntax in
diff --git a/src/proto_alpha/lib_protocol/test/unit/test_sc_rollup_storage.ml b/src/proto_alpha/lib_protocol/test/unit/test_sc_rollup_storage.ml
index 6b010c74b61d4edbae15cfd2e6a0c3680fb4f500..165e49f55f234b7e05728fe335df8ac50079458d 100644
--- a/src/proto_alpha/lib_protocol/test/unit/test_sc_rollup_storage.ml
+++ b/src/proto_alpha/lib_protocol/test/unit/test_sc_rollup_storage.ml
@@ -2340,6 +2340,53 @@ let test_concurrent_refinement_cement () =
   in
   assert_commitment_hash_equal ~loc:__LOC__ ctxt c1 c2
 
+let test_zero_tick_commitment_cannot_change_state () =
+  let* ctxt, rollup, genesis_hash, staker =
+    originate_rollup_and_deposit_with_one_staker ()
+  in
+  let level = valid_inbox_level ctxt in
+  let commitment =
+    Commitment_repr.
+      {
+        predecessor = genesis_hash;
+        inbox_level = level 1l;
+        number_of_messages = number_of_messages_exn 3l;
+        number_of_ticks = number_of_ticks_exn 1232909l;
+        compressed_state = Sc_rollup_repr.State_hash.zero;
+      }
+  in
+  let* c1, _level, ctxt =
+    lift
+    @@ Sc_rollup_stake_storage.Internal_for_tests.refine_stake
+         ctxt
+         rollup
+         staker
+         commitment
+  in
+  let commitment =
+    Commitment_repr.
+      {
+        predecessor = c1;
+        inbox_level = level 2l;
+        number_of_messages = number_of_messages_exn 0l;
+        number_of_ticks = number_of_ticks_exn 0l;
+        compressed_state =
+          Sc_rollup_repr.State_hash.context_hash_to_state_hash
+            (Context_hash.hash_string ["wxyz"]);
+      }
+  in
+  let* () =
+    assert_fails_with
+      ~loc:__LOC__
+      (Sc_rollup_stake_storage.Internal_for_tests.refine_stake
+         ctxt
+         rollup
+         staker
+         commitment)
+      Sc_rollup_errors.Sc_rollup_state_change_on_zero_tick_commitment
+  in
+  assert_true ctxt
+
 let check_gas_consumed ~since ~until =
   let open Raw_context in
   let as_cost = Gas_limit_repr.cost_of_gas @@ gas_consumed ~since ~until in
@@ -3059,6 +3106,10 @@ let tests =
       "Refinement operations are commutative (cement)"
       `Quick
       test_concurrent_refinement_cement;
+    Tztest.tztest
+      "A commitment with zero ticks shouldn't change the state"
+      `Quick
+      test_zero_tick_commitment_cannot_change_state;
     Tztest.tztest
       "Retrieval of in-memory message inbox consumes gas"
       `Quick
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- consecutive commitments.out b/tezt/tests/expected/sc_rollup.ml/Alpha- consecutive commitments.out
index 0ea5d7784185518ea26afdbda4a448fcfb518d1d..1d5e61040091f82add59708293a7f1f69a8ded76 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- consecutive commitments.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- consecutive commitments.out	
@@ -30,7 +30,7 @@ This sequence of operations was run:
         storage fees ........................... +ꜩ1.6565
 
 
-./tezos-client --wait none publish commitment from '[PUBLIC_KEY_HASH]' for sc rollup '[SC_ROLLUP_HASH]' with compressed state scs11VNjWyZw4Tgbvsom8epQbox86S2CKkE1UAZkXMM7Pj8MQMLzMf at inbox level 32 and predecessor '[SC_ROLLUP_COMMITMENT_HASH]' and number of messages 0 and number of ticks 0
+./tezos-client --wait none publish commitment from '[PUBLIC_KEY_HASH]' for sc rollup '[SC_ROLLUP_HASH]' with compressed state scs11VNjWyZw4Tgbvsom8epQbox86S2CKkE1UAZkXMM7Pj8MQMLzMf at inbox level 32 and predecessor '[SC_ROLLUP_COMMITMENT_HASH]' and number of messages 0 and number of ticks 1
 Node is bootstrapped.
 Estimated gas: 6251.140 units (will add 100 for safety)
 Estimated storage: no bytes added
@@ -55,7 +55,7 @@ This sequence of operations was run:
                          inbox_level: 32
                          predecessor: [SC_ROLLUP_COMMITMENT_HASH]
                          number_of_messages: 0
-                         number_of_ticks: 0 in the smart contract rollup at address [SC_ROLLUP_HASH]
+                         number_of_ticks: 1 in the smart contract rollup at address [SC_ROLLUP_HASH]
       This smart contract rollup commitment publishing was successfully applied
       Consumed gas: 6251.140
       Hash of commit: [SC_ROLLUP_COMMITMENT_HASH]
@@ -65,7 +65,7 @@ This sequence of operations was run:
         Frozen_bonds([PUBLIC_KEY_HASH],[SC_ROLLUP_HASH]) ... +ꜩ10000
 
 
-./tezos-client --wait none publish commitment from '[PUBLIC_KEY_HASH]' for sc rollup '[SC_ROLLUP_HASH]' with compressed state scs11VNjWyZw4Tgbvsom8epQbox86S2CKkE1UAZkXMM7Pj8MQMLzMf at inbox level 62 and predecessor '[SC_ROLLUP_COMMITMENT_HASH]' and number of messages 0 and number of ticks 0
+./tezos-client --wait none publish commitment from '[PUBLIC_KEY_HASH]' for sc rollup '[SC_ROLLUP_HASH]' with compressed state scs11VNjWyZw4Tgbvsom8epQbox86S2CKkE1UAZkXMM7Pj8MQMLzMf at inbox level 62 and predecessor '[SC_ROLLUP_COMMITMENT_HASH]' and number of messages 0 and number of ticks 1
 Node is bootstrapped.
 Estimated gas: 4479.904 units (will add 100 for safety)
 Estimated storage: no bytes added
@@ -90,7 +90,7 @@ This sequence of operations was run:
                          inbox_level: 62
                          predecessor: [SC_ROLLUP_COMMITMENT_HASH]
                          number_of_messages: 0
-                         number_of_ticks: 0 in the smart contract rollup at address [SC_ROLLUP_HASH]
+                         number_of_ticks: 1 in the smart contract rollup at address [SC_ROLLUP_HASH]
       This smart contract rollup commitment publishing was successfully applied
       Consumed gas: 4479.904
       Hash of commit: [SC_ROLLUP_COMMITMENT_HASH]
diff --git a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (too_many_m.out b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (too_many_m.out
index 9d957bd08d7e38445eba2f56ac2cf6313e215929..923def4442d96f8602f55feabb9c9f5128359480 100644
--- a/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (too_many_m.out	
+++ b/tezt/tests/expected/sc_rollup.ml/Alpha- observing the correct maintenance of inbox in the rollup node (too_many_m.out	
@@ -834,7 +834,4 @@ This simulation failed:
       This operation FAILED.
 
 Error:
-  { "id":
-    "proto.alpha.Sc_rollup_max_number_of_messages_reached_for_commitment_period",
-  "description": "Maximum number of messages reached for commitment period",
-  "data": {} }
+  Maximum number of messages reached for commitment period
diff --git a/tezt/tests/sc_rollup.ml b/tezt/tests/sc_rollup.ml
index 4b86ffd010befe28b5da5fd5d37f0102ffa4c7b0..86c63f1174a0fdbba4ac882bca7b8c06bd5cf887 100644
--- a/tezt/tests/sc_rollup.ml
+++ b/tezt/tests/sc_rollup.ml
@@ -1968,7 +1968,7 @@ let publish_dummy_commitment ~inbox_level ~predecessor ~sc_rollup ~src client =
       inbox_level;
       predecessor;
       number_of_messages = 0;
-      number_of_ticks = 0;
+      number_of_ticks = 1;
     }
   in