diff --git a/contracts/staking/src/contract.rs b/contracts/staking/src/contract.rs
index ed92229278..02e9c71793 100644
--- a/contracts/staking/src/contract.rs
+++ b/contracts/staking/src/contract.rs
@@ -86,11 +86,11 @@ pub fn transfer(
     let sender_raw = deps.api.canonical_address(&info.sender)?;
 
     let mut accounts = balances(deps.storage);
-    accounts.update(&sender_raw, |balance: Option<Uint128>| {
-        balance.unwrap_or_default() - send
+    accounts.update(&sender_raw, |balance: Option<Uint128>| -> StdResult<_> {
+        Ok(balance.unwrap_or_default().checked_sub(send)?)
     })?;
     accounts.update(&rcpt_raw, |balance: Option<Uint128>| -> StdResult<_> {
-        Ok(balance.unwrap_or_default() + send)
+        Ok(balance.unwrap_or_default().checked_add(send)?)
     })?;
 
     let res = Response {
@@ -123,7 +123,7 @@ fn get_bonded(querier: &QuerierWrapper, contract: &HumanAddr) -> StdResult<Uint1
                 denom, &d.amount.denom
             )))
         } else {
-            Ok(acc + d.amount.amount)
+            Ok(acc.checked_add(d.amount.amount)?)
         }
     })
 }
@@ -164,13 +164,13 @@ pub fn bond(deps: DepsMut, env: Env, info: MessageInfo) -> StdResult<Response> {
     } else {
         payment.amount.multiply_ratio(supply.issued, bonded)
     };
-    supply.bonded = bonded + payment.amount;
-    supply.issued += to_mint;
+    supply.bonded = bonded.checked_add(payment.amount)?;
+    supply.issued = supply.issued.checked_add(to_mint)?;
     totals.save(&supply)?;
 
     // update the balance of the sender
     balances(deps.storage).update(&sender_raw, |balance| -> StdResult<_> {
-        Ok(balance.unwrap_or_default() + to_mint)
+        Ok(balance.unwrap_or_default().checked_add(to_mint)?)
     })?;
 
     // bond them to the validator
@@ -209,12 +209,12 @@ pub fn unbond(deps: DepsMut, env: Env, info: MessageInfo, amount: Uint128) -> St
     // deduct all from the account
     let mut accounts = balances(deps.storage);
     accounts.update(&sender_raw, |balance| -> StdResult<_> {
-        balance.unwrap_or_default() - amount
+        Ok(balance.unwrap_or_default().checked_sub(amount)?)
     })?;
     if tax > Uint128(0) {
         // add tax to the owner
         accounts.update(&invest.owner, |balance: Option<Uint128>| -> StdResult<_> {
-            Ok(balance.unwrap_or_default() + tax)
+            Ok(balance.unwrap_or_default().checked_add(tax)?)
         })?;
     }
 
@@ -231,12 +231,12 @@ pub fn unbond(deps: DepsMut, env: Env, info: MessageInfo, amount: Uint128) -> St
     let unbond = remainder.multiply_ratio(bonded, supply.issued);
     supply.bonded = (bonded - unbond)?;
     supply.issued = (supply.issued - remainder)?;
-    supply.claims += unbond;
+    supply.claims = supply.claims.checked_add(unbond)?;
     totals.save(&supply)?;
 
     // add a claim to this user to get their tokens after the unbonding period
     claims(deps.storage).update(&sender_raw, |claim| -> StdResult<_> {
-        Ok(claim.unwrap_or_default() + unbond)
+        Ok(claim.unwrap_or_default().checked_add(unbond)?)
     })?;
 
     // unbond them
@@ -273,10 +273,10 @@ pub fn claim(deps: DepsMut, env: Env, info: MessageInfo) -> StdResult<Response>
     // check how much to send - min(balance, claims[sender]), and reduce the claim
     let sender_raw = deps.api.canonical_address(&info.sender)?;
     let mut to_send = balance.amount;
-    claims(deps.storage).update(sender_raw.as_slice(), |claim| {
+    claims(deps.storage).update(sender_raw.as_slice(), |claim| -> StdResult<_> {
         let claim = claim.ok_or_else(|| StdError::generic_err("no claim for this address"))?;
         to_send = to_send.min(claim);
-        claim - to_send
+        Ok(claim.checked_sub(to_send)?)
     })?;
 
     // update total supply (lower claim)
@@ -356,12 +356,12 @@ pub fn _bond_all_tokens(
         balance.amount = (balance.amount - supply.claims)?;
         // this just triggers the "no op" case if we don't have min_withdrawal left to reinvest
         (balance.amount - invest.min_withdrawal)?;
-        supply.bonded += balance.amount;
+        supply.bonded = supply.bonded.checked_add(balance.amount)?;
         Ok(supply)
     }) {
         Ok(_) => {}
         // if it is below the minimum, we do a no-op (do not revert other state from withdrawal)
-        Err(StdError::Underflow { .. }) => return Ok(Response::default()),
+        Err(StdError::Overflow(_)) => return Ok(Response::default()),
         Err(e) => return Err(e.into()),
     }