diff --git a/test/unit/BPool/BPool_JoinswapExternAmountIn.t.sol b/test/unit/BPool/BPool_JoinswapExternAmountIn.t.sol
index e71a1cf2..04981553 100644
--- a/test/unit/BPool/BPool_JoinswapExternAmountIn.t.sol
+++ b/test/unit/BPool/BPool_JoinswapExternAmountIn.t.sol
@@ -70,6 +70,8 @@ contract BPoolJoinswapExternAmountIn is BPoolBase, BNum {
   function test_WhenPreconditionsAreMet() external {
     // it sets reentrancy lock
     bPool.expectCall__setLock(_MUTEX_TAKEN);
+    // it queries the contracts token in balance
+    vm.expectCall(tokenIn, abi.encodeCall(IERC20.balanceOf, (address(bPool))));
     // it calls _pullUnderlying for token
     bPool.mock_call__pullUnderlying(tokenIn, address(this), tokenAmountIn);
     bPool.expectCall__pullUnderlying(tokenIn, address(this), tokenAmountIn);
diff --git a/test/unit/BPool/BPool_JoinswapExternAmountIn.tree b/test/unit/BPool/BPool_JoinswapExternAmountIn.tree
index 9f2b391a..6e49f3ab 100644
--- a/test/unit/BPool/BPool_JoinswapExternAmountIn.tree
+++ b/test/unit/BPool/BPool_JoinswapExternAmountIn.tree
@@ -12,6 +12,7 @@ BPool::JoinswapExternAmountIn
 └── when preconditions are met
     ├── it emits LOG_CALL event
     ├── it sets the reentrancy lock
+    ├── it queries the contracts token in balance
     ├── it emits LOG_JOIN event for token
     ├── it calls _pullUnderlying for token
     ├── it mints the pool shares