diff --git a/src/Crypto.php b/src/Crypto.php
index 144a01d..f96ba30 100755
--- a/src/Crypto.php
+++ b/src/Crypto.php
@@ -284,7 +284,7 @@ private static function plainDecrypt($ciphertext, $key, $iv)
         $method = self::CIPHER.'-'.self::CIPHER_MODE;
 
         self::ensureConstantExists("OPENSSL_RAW_DATA");
-        self::ensureFunctionExists("openssl_encrypt");
+        self::ensureFunctionExists("openssl_decrypt");
         $plaintext = \openssl_decrypt(
             $ciphertext,
             $method,