diff --git a/composer.json b/composer.json
index c6b532f..df03938 100644
--- a/composer.json
+++ b/composer.json
@@ -18,7 +18,7 @@
   ],
   "require": {
     "php": ">=5.6",
-    "phpseclib/phpseclib": ">=2.0.0"
+    "phpseclib/phpseclib": "^2.0.0"
   },
   "require-dev": {
     "phpunit/phpunit": "4.8.*"