diff --git a/packages/contracts/blend-adapter/src/lib.rs b/packages/contracts/blend-adapter/src/lib.rs
index 0702b4f9..1b20724e 100644
--- a/packages/contracts/blend-adapter/src/lib.rs
+++ b/packages/contracts/blend-adapter/src/lib.rs
@@ -42,7 +42,7 @@ fn b_tokens_to_usdc(b_tokens: i128, b_rate: i128) -> Result<i128, ContractError>
         .checked_mul(b_rate)
         .ok_or(ContractError::Overflow)?
         .checked_div(RATE_SCALAR)
-        .ok_or(ContractError::Overflow)
+        .ok_or(ContractError::DivisionByZero)
 }
 
 // ---------------------------------------------------------------------------
@@ -133,6 +133,11 @@ pub enum ContractError {
     AlreadyInitialized = 1,
     /// An intermediate arithmetic operation would overflow `i128`.
     Overflow = 2,
+    /// A `checked_div` returned `None` because the divisor was zero.
+    /// Distinct from `Overflow`: this points to a degenerate adapter state
+    /// (e.g. a zero `b_rate` from a broken Blend pool) rather than a genuine
+    /// arithmetic overflow.
+    DivisionByZero = 3,
     /// A state-mutating call was made before `initialize`.
     NotInitialized = 3,
 }
diff --git a/packages/contracts/vault/src/lib.rs b/packages/contracts/vault/src/lib.rs
index 2da40543..64cd5ce4 100644
--- a/packages/contracts/vault/src/lib.rs
+++ b/packages/contracts/vault/src/lib.rs
@@ -125,6 +125,10 @@ pub enum ContractError {
     NoAdapterPosition = 13,
     /// `migrate_adapter` was called with `max_slippage_bps > 10_000`.
     InvalidSlippageBps = 14,
+    /// A `checked_div` returned `None` because the divisor was zero.
+    /// Distinct from `Overflow`: this points to a degenerate adapter state
+    /// (e.g. zero `total_assets`) rather than a genuine arithmetic overflow.
+    DivisionByZero = 19,
     /// `withdraw` was called with a `min_usdc_out` floor and the actual
     /// amount out fell below it. Distinct from `WithdrawalTooSmall` (which
     /// fires when `usdc_out` rounds to zero): this fires when `usdc_out > 0`
@@ -208,7 +212,7 @@ impl MeridianVault {
         // Minting here would dilute every existing holder.
         if total_shares > 0 && total_assets <= 0 {
             return Err(ContractError::AdapterReportedNoAssets);
-        }
+        }https://github.com/drydocs/meridian/pull/671/conflict?name=packages%252Fcontracts%252Fvault%252Fsrc%252Flib.rs&ancestor_oid=5da2079f71a9c080d32edf55b78fafd79dbb877a&base_oid=9567e868a38dfec5c837a18cf35b890d6e172a59&head_oid=2da4054355f35c399d2f7f50c6c72e54bdc494b6
 
         // shares_to_mint = amount * (total_shares + OFFSET) / (total_assets + OFFSET)
         // The virtual offset makes the first-deposit price 1 share = 1 stroop while
@@ -220,6 +224,8 @@ impl MeridianVault {
                     .ok_or(ContractError::Overflow)?,
             )
             .ok_or(ContractError::Overflow)?
+            .checked_div(total_assets + OFFSET)
+            .ok_or(ContractError::DivisionByZero)?;
             .checked_div(
                 total_assets
                     .checked_add(OFFSET)
@@ -346,7 +352,7 @@ impl MeridianVault {
             .checked_mul(total_adapter_shares)
             .ok_or(ContractError::Overflow)?
             .checked_div(total_shares)
-            .ok_or(ContractError::Overflow)?;
+            .ok_or(ContractError::DivisionByZero)?;
 
         // Adapter redeems protocol shares, delivers USDC to vault, returns amount.
         let usdc_out = AdapterClient::new(&env, &adapter_addr)
@@ -384,7 +390,7 @@ impl MeridianVault {
             .checked_mul(shares)
             .ok_or(ContractError::Overflow)?
             .checked_div(caller_shares)
-            .ok_or(ContractError::Overflow)?;
+            .ok_or(ContractError::DivisionByZero)?;
         env.storage()
             .persistent()
             .set(&principal_key, &(principal - principal_out));
@@ -676,7 +682,7 @@ impl MeridianVault {
             .checked_mul(10_000i128 - max_slippage_bps as i128)
             .ok_or(ContractError::Overflow)?
             .checked_div(10_000i128)
-            .ok_or(ContractError::Overflow)?;
+            .ok_or(ContractError::DivisionByZero)?;
         if value_after < min_acceptable {
             return Err(ContractError::MigrationValueDrift);
         }