diff --git a/contracts/partials/ITTDex.ligo b/contracts/partials/ITTDex.ligo
index d6e291f0..3eefe12e 100644
--- a/contracts/partials/ITTDex.ligo
+++ b/contracts/partials/ITTDex.ligo
@@ -90,10 +90,19 @@ type token_to_token_route_params is
     receiver              : address; (* tokens receiver *)
   ]
 
+type initialize_params is
+  [@layout:comb]
+  record [
+    pair            : tokens_info; (* exchange pair info *)
+    token_a_in      : nat; (* min amount of tokens A invested  *)
+    token_b_in      : nat; (* min amount of tokens B invested *)
+  ]
+
 type invest_liquidity_params is
   [@layout:comb]
   record [
     pair            : tokens_info; (* exchange pair info *)
+    shares          : nat; (* the amount of shares to receive *)
     token_a_in      : nat; (* min amount of tokens A invested  *)
     token_b_in      : nat; (* min amount of tokens B invested *)
   ]
@@ -108,7 +117,7 @@ type divest_liquidity_params is
   ]
 
 type dex_action is
-| AddPair                 of invest_liquidity_params  (* sets initial liquidity *)
+| AddPair                 of initialize_params  (* sets initial liquidity *)
 | Swap                    of token_to_token_route_params  (* exchanges token to another token and sends them to receiver *)
 | Invest                  of invest_liquidity_params  (* mints min shares after investing tokens *)
 | Divest                  of divest_liquidity_params  (* burns shares and sends tokens to the owner *)
diff --git a/contracts/partials/TTMethodDex.ligo b/contracts/partials/TTMethodDex.ligo
index cd305bbb..d8fb092d 100644
--- a/contracts/partials/TTMethodDex.ligo
+++ b/contracts/partials/TTMethodDex.ligo
@@ -483,29 +483,19 @@ function invest_liquidity(
         if pair.token_a_pool * pair.token_b_pool = 0n
         then failwith("Dex/not-launched") else skip;
 
-        (* calculate purchased tokens *)
-        const shares_a_purchased : nat =
-          params.token_a_in * pair.total_supply / pair.token_a_pool;
-        const shares_b_purchased : nat =
-          params.token_b_in * pair.total_supply / pair.token_b_pool;
-        const shares_purchased : nat =
-          if shares_a_purchased < shares_b_purchased
-          then shares_a_purchased
-          else shares_b_purchased;
-
         (* ensure purchsed shares satisfy required minimum *)
-        if shares_purchased = 0n
+        if params.shares = 0n
         then failwith("Dex/wrong-params") else skip;
 
         (* calculate tokens to be withdrawn *)
         const tokens_a_required : nat =
-          shares_purchased * pair.token_a_pool / pair.total_supply;
-        if shares_purchased * pair.token_a_pool >
+          params.shares * pair.token_a_pool / pair.total_supply;
+        if params.shares * pair.token_a_pool >
           tokens_a_required * pair.total_supply
         then tokens_a_required := tokens_a_required + 1n else skip;
         const tokens_b_required : nat =
-          shares_purchased * pair.token_b_pool / pair.total_supply;
-        if shares_purchased * pair.token_b_pool >
+          params.shares * pair.token_b_pool / pair.total_supply;
+        if params.shares * pair.token_b_pool >
           tokens_b_required * pair.total_supply
         then tokens_b_required := tokens_b_required + 1n else skip;
 
@@ -523,7 +513,7 @@ function invest_liquidity(
         const share : nat = account.balance;
 
         (* update user's shares *)
-        account.balance := share + shares_purchased;
+        account.balance := share + params.shares;
         s.ledger[(Tezos.sender, token_id)] := account;
 
         (* update reserves *)
@@ -531,7 +521,7 @@ function invest_liquidity(
         pair.token_b_pool := pair.token_b_pool + tokens_b_required;
 
         (* update total number of shares *)
-        pair.total_supply := pair.total_supply + shares_purchased;
+        pair.total_supply := pair.total_supply + params.shares;
         s.pairs[token_id] := pair;
 
         (* prepare operations to get initial liquidity *)
diff --git a/test/helpers/ttdexFA2.ts b/test/helpers/ttdexFA2.ts
index 45d195cf..e5db4b03 100644
--- a/test/helpers/ttdexFA2.ts
+++ b/test/helpers/ttdexFA2.ts
@@ -294,6 +294,7 @@ export class TTDex extends TokenFA2 {
         "invest",
         pair.token_a_address,
         pair.token_a_id,
+        minShares,
         standard.toLowerCase() == "mixed" ? "fa2" : standard.toLowerCase(),
         null,
         pair.token_b_address,
@@ -301,8 +302,7 @@ export class TTDex extends TokenFA2 {
         standard.toLowerCase() == "mixed" ? "fa12" : standard.toLowerCase(),
         null,
         tokenAAmount,
-        tokenBAmount,
-        minShares
+        tokenBAmount
       )
       .send();
     await confirmOperation(tezos, operation.hash);