diff --git a/src/handlers/generate-erc721-permit.ts b/src/handlers/generate-erc721-permit.ts
index 39ebced..569c273 100644
--- a/src/handlers/generate-erc721-permit.ts
+++ b/src/handlers/generate-erc721-permit.ts
@@ -68,9 +68,23 @@ export async function generateErc721PermitSignature(
     _userId = contextOrPermitPayload.userId;
   } else {
     const { NFT_MINTER_PRIVATE_KEY, NFT_CONTRACT_ADDRESS } = contextOrPermitPayload.env;
+
+    _logger = contextOrPermitPayload.logger;
+
+    if (!NFT_MINTER_PRIVATE_KEY) {
+      const errorMessage = "NFT minter private key is not defined";
+      _logger.error(errorMessage);
+      throw new Error(errorMessage);
+    }
+
+    if (!NFT_CONTRACT_ADDRESS) {
+      const errorMessage = "NFT contract address is not defined";
+      _logger.error(errorMessage);
+      throw new Error(errorMessage);
+    }
+
     const { evmNetworkId } = contextOrPermitPayload.config;
     const adapters = contextOrPermitPayload.adapters;
-    _logger = contextOrPermitPayload.logger;
     _nftContractAddress = NFT_CONTRACT_ADDRESS;
     _evmNetworkId = evmNetworkId;
     _nftMinterPrivateKey = NFT_MINTER_PRIVATE_KEY;
@@ -102,12 +116,6 @@ export async function generateErc721PermitSignature(
     throw new Error("Provider is not defined");
   }
 
-  if (!_nftContractAddress) {
-    const errorMessage = "NFT contract address is not defined";
-    _logger.error(errorMessage);
-    throw new Error(errorMessage);
-  }
-
   let adminWallet;
 
   try {
diff --git a/src/types/env.ts b/src/types/env.ts
index a816449..8994469 100644
--- a/src/types/env.ts
+++ b/src/types/env.ts
@@ -6,8 +6,8 @@ export const envSchema = T.Object({
   GITHUB_TOKEN: T.String(),
   SUPABASE_URL: T.String(),
   SUPABASE_KEY: T.String(),
-  NFT_MINTER_PRIVATE_KEY: T.String(),
-  NFT_CONTRACT_ADDRESS: T.String(),
+  NFT_MINTER_PRIVATE_KEY: T.Optional(T.String()),
+  NFT_CONTRACT_ADDRESS: T.Optional(T.String()),
 });
 
 export type Env = StaticDecode<typeof envSchema>;
diff --git a/tests/generate-erc721-permit.test.ts b/tests/generate-erc721-permit.test.ts
index b65da8c..86b2638 100644
--- a/tests/generate-erc721-permit.test.ts
+++ b/tests/generate-erc721-permit.test.ts
@@ -117,7 +117,7 @@ describe("generateErc721PermitSignature", () => {
 
   it("should throw an error if NFT minter private key is not defined", async () => {
     delete process.env.NFT_MINTER_PRIVATE_KEY;
-    await expect(generateErc721PermitSignature(context, "123", "contribution")).rejects.toThrow("Failed to" + " instantiate wallet");
+    await expect(generateErc721PermitSignature(context, "123", "contribution")).rejects.toThrow("NFT minter" + " private key" + " is not defined");
     expect(context.logger.error).toHaveBeenCalled();
   });