diff --git a/src/proto_alpha/lib_protocol/main.ml b/src/proto_alpha/lib_protocol/main.ml
index b226dc5417..cef4feef6e 100644
--- a/src/proto_alpha/lib_protocol/main.ml
+++ b/src/proto_alpha/lib_protocol/main.ml
@@ -64,10 +64,9 @@ type operation = Alpha_context.packed_operation = {
 
 let acceptable_pass = Alpha_context.Operation.acceptable_pass
 
-let max_block_length = Alpha_context.Block_header.max_header_length
+let max_block_length = max_int
 
-let max_operation_data_length =
-  Alpha_context.Constants.max_operation_data_length
+let max_operation_data_length = max_int
 
 let validation_passes =
   let open Alpha_context.Constants in
@@ -83,7 +82,7 @@ let validation_passes =
         max_op = Some max_anon_ops_per_block;
       };
       (* 512kB *)
-      {max_size = 512 * 1024; max_op = None};
+      {max_size = max_int; max_op = None};
     ]
 
 let rpc_services =