diff --git a/src/proto_alpha/lib_protocol/init_storage.ml b/src/proto_alpha/lib_protocol/init_storage.ml
index e6e33340adaf6adb9a5358071ddc767c28ee9029..5ccc921fe58f00fc492e5e9283df393adea28456 100644
--- a/src/proto_alpha/lib_protocol/init_storage.ml
+++ b/src/proto_alpha/lib_protocol/init_storage.ml
@@ -145,6 +145,17 @@ let migrate_stake_distribution_for_o ctxt =
       let distr = List.map (fun (pkh, stake) -> (pkh, convert stake)) distr in
       Storage.Stake.Selected_distribution_for_cycle.update ctxt cycle distr)
 
+(** Initializes the total supply at the beginning of O
+    Uses an estimation of the total supply at the activation of O.
+    This value can be refined at the beginning of P to have a
+    perfectly accurate ammount.
+
+    Remove me in P. *)
+let initialize_total_supply_for_o ctxt =
+  Storage.Contract.Total_supply.add
+    ctxt
+    (Tez_repr.of_mutez_exn 940_000_000_000_000L)
+
 let prepare_first_block _chain_id ctxt ~typecheck ~level ~timestamp ~predecessor
     =
   Raw_context.prepare_first_block ~level ~timestamp ctxt
@@ -161,6 +172,7 @@ let prepare_first_block _chain_id ctxt ~typecheck ~level ~timestamp ~predecessor
       Raw_level_repr.of_int32 level >>?= fun level ->
       Storage.Tenderbake.First_level_of_protocol.init ctxt level
       >>=? fun ctxt ->
+      Storage.Contract.Total_supply.add ctxt Tez_repr.zero >>= fun ctxt ->
       Storage.Block_round.init ctxt Round_repr.zero >>=? fun ctxt ->
       let init_commitment (ctxt, balance_updates)
           Commitment_repr.{blinded_public_key_hash; amount} =
@@ -212,7 +224,8 @@ let prepare_first_block _chain_id ctxt ~typecheck ~level ~timestamp ~predecessor
       Raw_level_repr.of_int32 level >>?= fun level ->
       Storage.Tenderbake.First_level_of_protocol.update ctxt level
       >>=? fun ctxt ->
-      migrate_stake_distribution_for_o ctxt >>=? fun ctxt -> return (ctxt, []))
+      migrate_stake_distribution_for_o ctxt >>=? fun ctxt ->
+      initialize_total_supply_for_o ctxt >>= fun ctxt -> return (ctxt, []))
   >>=? fun (ctxt, balance_updates) ->
   List.fold_left_es patch_script ctxt Legacy_script_patches.addresses_to_patch
   >>=? fun ctxt ->
diff --git a/src/proto_alpha/lib_protocol/storage.ml b/src/proto_alpha/lib_protocol/storage.ml
index 86e52b2cf4076d971e8d47305c9c8c0365f415d4..2a2850b7f2ce336d827709472e943900b780649d 100644
--- a/src/proto_alpha/lib_protocol/storage.ml
+++ b/src/proto_alpha/lib_protocol/storage.ml
@@ -407,6 +407,13 @@ module Contract = struct
         let name = ["total_frozen_bonds"]
       end)
       (Tez_repr)
+
+  module Total_supply =
+    Make_single_data_storage (Registered) (Raw_context)
+      (struct
+        let name = ["total_supply"]
+      end)
+      (Tez_repr)
 end
 
 module type NEXT = sig
diff --git a/src/proto_alpha/lib_protocol/storage.mli b/src/proto_alpha/lib_protocol/storage.mli
index a82d10ee85a5042ff486251e965114c77bf70b48..b1280cff1f984ab5abe2a312d8823a8257597271 100644
--- a/src/proto_alpha/lib_protocol/storage.mli
+++ b/src/proto_alpha/lib_protocol/storage.mli
@@ -229,6 +229,10 @@ module Contract : sig
       with type key = Contract_repr.t
        and type value = Tez_repr.t
        and type t := Raw_context.t
+
+  (** Stores the amount of tokens currently present on chain *)
+  module Total_supply :
+    Single_data_storage with type value = Tez_repr.t and type t := Raw_context.t
 end
 
 module Big_map : sig