diff --git a/src/types/lib.ts b/src/types/lib.ts
index f61c00c0e..b523919fd 100644
--- a/src/types/lib.ts
+++ b/src/types/lib.ts
@@ -21,7 +21,7 @@ export type DeployContractPayload = {
 
 export type DeclareContractPayload = {
   contract: CompiledContract | string;
-  classHash: string; // Once the classHash is included in CompiledContract, this can be removedf
+  classHash: BigNumberish; // Once the classHash is included in CompiledContract, this can be removedf
 };
 
 export type DeclareContractTransaction = {
diff --git a/src/types/signer.ts b/src/types/signer.ts
index bece1d71a..db674c449 100644
--- a/src/types/signer.ts
+++ b/src/types/signer.ts
@@ -9,7 +9,7 @@ export interface InvocationsSignerDetails extends Required<InvocationsDetails> {
 
 export interface DeclareSignerDetails {
   // contractClass: ContractClass,  // Should be used once class hash is present in ContractClass
-  classHash: string;
+  classHash: BigNumberish;
   senderAddress: BigNumberish;
   chainId: StarknetChainId;
   maxFee: BigNumberish;
diff --git a/src/utils/hash.ts b/src/utils/hash.ts
index 3bec3bb93..42f273413 100644
--- a/src/utils/hash.ts
+++ b/src/utils/hash.ts
@@ -149,7 +149,7 @@ export function calculateDeployTransactionHash(
 
 export function calculateDeclareTransactionHash(
   // contractClass: ContractClass, // Should be used once class hash is present in ContractClass
-  classHash: string,
+  classHash: BigNumberish,
   senderAddress: BigNumberish,
   version: BigNumberish,
   maxFee: BigNumberish,