diff --git a/CHANGES.rst b/CHANGES.rst
index b6b8c3a316b2655c5c12be9118ce56204c317271..78bd4b12bf67ce4a072cbec1c92532ab306d2a7b 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -189,6 +189,8 @@ Smart Rollup client
 - Fix a critical bug that could lead to data loss when chain
   reorganizations happen while a GC is running. (MR :gl:`!11358`)
 
+- Fix issue with constants fetching during protocol migration. (MR :gl:`!11804`)
+
 Smart Rollup WASM Debugger
 --------------------------
 
diff --git a/src/lib_smart_rollup_node/protocol_plugins.ml b/src/lib_smart_rollup_node/protocol_plugins.ml
index f5e3c0b4294e50f8511c0839e4d372a2990de721..df9daee9d5d255e7af1d9968e6a760911044fed3 100644
--- a/src/lib_smart_rollup_node/protocol_plugins.ml
+++ b/src/lib_smart_rollup_node/protocol_plugins.ml
@@ -100,7 +100,8 @@ let constants_cache =
   let cache_size = 3 in
   Constants_cache.create cache_size
 
-let get_constants_of_protocol (node_ctxt : _ Node_context.t) protocol_hash =
+let get_constants_of_protocol ?level (node_ctxt : _ Node_context.t)
+    protocol_hash =
   let open Lwt_result_syntax in
   if Protocol_hash.(protocol_hash = node_ctxt.current_protocol.hash) then
     return node_ctxt.current_protocol.constants
@@ -108,10 +109,18 @@ let get_constants_of_protocol (node_ctxt : _ Node_context.t) protocol_hash =
     let retrieve protocol_hash =
       let*? plugin = proto_plugin_for_protocol protocol_hash in
       let module Plugin = (val plugin) in
-      let* (First_known l | Activation_level l) =
-        Node_context.protocol_activation_level node_ctxt protocol_hash
+      let* level =
+        match level with
+        | None ->
+            let+ (First_known l | Activation_level l) =
+              Node_context.protocol_activation_level node_ctxt protocol_hash
+            in
+            l
+        | Some l -> return l
       in
-      Plugin.Layer1_helpers.retrieve_constants ~block:(`Level l) node_ctxt.cctxt
+      Plugin.Layer1_helpers.retrieve_constants
+        ~block:(`Level level)
+        node_ctxt.cctxt
     in
     Constants_cache.bind_or_put
       constants_cache
@@ -122,7 +131,7 @@ let get_constants_of_protocol (node_ctxt : _ Node_context.t) protocol_hash =
 let get_constants_of_level node_ctxt level =
   let open Lwt_result_syntax in
   let* {protocol; _} = Node_context.protocol_of_level node_ctxt level in
-  get_constants_of_protocol node_ctxt protocol
+  get_constants_of_protocol ~level node_ctxt protocol
 
 let get_constants_of_block_hash node_ctxt block_hash =
   let open Lwt_result_syntax in
diff --git a/src/lib_smart_rollup_node/protocol_plugins.mli b/src/lib_smart_rollup_node/protocol_plugins.mli
index b7bb6604d4c98963135f273bfc271189611a0857..9a8b83afaf68dab755c0a56a4cf079371c31ea70 100644
--- a/src/lib_smart_rollup_node/protocol_plugins.mli
+++ b/src/lib_smart_rollup_node/protocol_plugins.mli
@@ -65,12 +65,6 @@ val last_proto_plugin : _ Node_context.t -> proto_plugin tzresult Lwt.t
     depending on the context.
 *)
 
-(** Retrieve constants for a given protocol (values are cached). *)
-val get_constants_of_protocol :
-  _ Node_context.t ->
-  Protocol_hash.t ->
-  Rollup_constants.protocol_constants tzresult Lwt.t
-
 (** Retrieve constants for a given level (values are cached). *)
 val get_constants_of_level :
   _ Node_context.t ->
diff --git a/src/lib_smart_rollup_node/rollup_node_daemon.ml b/src/lib_smart_rollup_node/rollup_node_daemon.ml
index d18f5ab0e1b2745b4e88e428ea14a2a2ca3249c3..75468413300b6b099618d09f9a6b8a73324f5384 100644
--- a/src/lib_smart_rollup_node/rollup_node_daemon.ml
+++ b/src/lib_smart_rollup_node/rollup_node_daemon.ml
@@ -69,7 +69,13 @@ let handle_protocol_migration ~catching_up state (head : Layer1.header) =
   in
   let*? new_plugin = Protocol_plugins.proto_plugin_for_protocol new_protocol in
   let* constants =
-    Protocol_plugins.get_constants_of_protocol state.node_ctxt new_protocol
+    (* If the head is the last block of the protocol, i.e. a migration block, we
+       need to use its predecessor to fetch constants from the correct
+       context. For the other cases, the context of the predecessor is always
+       the same protocol. *)
+    Protocol_plugins.get_constants_of_level
+      state.node_ctxt
+      (Int32.pred head.level)
   in
   let new_protocol =
     {