diff --git a/composer.json b/composer.json
index 06fa941..8101ca3 100644
--- a/composer.json
+++ b/composer.json
@@ -26,7 +26,7 @@
     "require": {
         "php": "^8.4",
         "illuminate/contracts": "^11.0||^12.0",
-        "kornrunner/ethereum-address": "^0.3.0",
+        "kornrunner/ethereum-address": "^0.4.0",
         "kornrunner/keccak": "^1.1",
         "spatie/laravel-package-tools": "^1.16",
         "web3p/ethereum-tx": "^0.4.3"
diff --git a/src/Exceptions/RequirementException.php b/src/Exceptions/RequirementException.php
new file mode 100644
index 0000000..ebc0e6a
--- /dev/null
+++ b/src/Exceptions/RequirementException.php
@@ -0,0 +1,6 @@
+<?php
+
+namespace Farbcode\LaravelEvm\Exceptions;
+
+// Thrown when a mandatory PHP extension or runtime prerequisite is missing.
+class RequirementException extends EvmException {}
diff --git a/src/LaravelEvmServiceProvider.php b/src/LaravelEvmServiceProvider.php
index 2738518..6fdd94c 100644
--- a/src/LaravelEvmServiceProvider.php
+++ b/src/LaravelEvmServiceProvider.php
@@ -16,6 +16,7 @@
 use Farbcode\LaravelEvm\Crypto\LocalNonceManager;
 use Farbcode\LaravelEvm\Crypto\PrivateKeySigner;
 use Farbcode\LaravelEvm\Crypto\TxBuilderEip1559;
+use Farbcode\LaravelEvm\Exceptions\RequirementException;
 use Farbcode\LaravelEvm\Support\LogFilterBuilder;
 use Farbcode\LaravelEvm\Support\SimpleFeePolicy;
 use Illuminate\Contracts\Foundation\Application;
@@ -39,8 +40,14 @@ public function configurePackage(Package $package): void
             ]);
     }
 
-    public function packageRegistered()
+    public function packageRegistered(): void
     {
+        // Runtime environment guard: ensure GMP extension is loaded.
+        // This package relies on big integer math (Keccak, RLP, transaction signing).
+        if (! extension_loaded('gmp')) {
+            throw new RequirementException('The GMP PHP extension is required for laravel-evm. Please enable it: e.g. install with `apt install php-gmp` or add `extension=gmp` to your php.ini and restart PHP-FPM / CLI.');
+        }
+
         $this->app->singleton(RpcClient::class, fn () => new RpcHttpClient(
             config('evm.rpc_urls'),
             (int) config('evm.chain_id', 137)