diff --git a/packages/evm-client/src/contract/types/Contract.ts b/packages/evm-client/src/contract/types/Contract.ts
index ddbc541..0d94c82 100644
--- a/packages/evm-client/src/contract/types/Contract.ts
+++ b/packages/evm-client/src/contract/types/Contract.ts
@@ -167,7 +167,7 @@ export interface ContractWriteOptions {
   /**
    * A callback for when the transaction has been mined.
    */
-  onTransactionMined?: (hash: `0x${string}`) => void;
+  onTransactionMined?(hash: `0x${string}`): void;
 }
 
 export type ContractWriteArgs<